| [ CnUnix ] in KIDS 글 쓴 이(By): sojin (윤 진수) 날 짜 (Date): 1993년08월13일(금) 16시43분55초 KDT 제 목(Title): UNIX용 하드웨어 가이드 (fwd) From jksong Thu Aug 12 02:39:54 1993 Return-Path: <jksong> Received: by cosmos.kaist.ac.kr (4.1/SMI-4.1) id AA12197; Thu, 12 Aug 93 02:39:53 KST From: jksong (Song Jaekyung) Message-Id: <9308111739.AA12197@cosmos.kaist.ac.kr> Errors-To: Postmaster@cosmos.kaist.ac.kr Subject: PC-Clone UNIX Hardware Buyer's Guide (fwd) To: jisyoon (Jinsoo Yoon) Date: Thu, 12 Aug 93 2:39:52 KST X-Mailer: ELM [version 2.3 PL11] Status: OR (Eric S. Raymond) writes: >From umd5.umd.edu!haven.umd.edu!darwin.sura.net!math.ohio-state.edu!cs.utexas.edu!tamsun.tamu.edu!bloom-beacon.mit.edu!news.kei.com!ub!dsinc!gvls1!boojum!esr Thu Aug 12 02:37:38 1993 From: esr@snark.thyrsus.com (Eric S. Raymond) Path: umd5.umd.edu!haven.umd.edu!darwin.sura.net!math.ohio-state.edu!cs.utexas.edu!tamsun.tamu.edu!bloom-beacon.mit.edu!news.kei.com!ub!dsinc!gvls1!boojum!esr Newsgroups: comp.unix.sys5.r4,comp.unix.pc-clone.32bit,comp.sys.intel,comp.os.linux.announce,news.answers Subject: PC-Clone UNIX Hardware Buyer's Guide Message-ID: <1mNyW2#M9B6mD216CrtH5dJCqc4MlOSk=esr@boojum.thyrsus.com> Date: 8 Aug 93 16:31:24 GMT Expires: 4 Sep 93 23:30:00 GMT Sender: esr@boojum.thyrsus.com (Eric S. Raymond) Followup-To: comp.unix.pc-clone.32bit Distribution: world Summary: Tips on how and where to buy hardware for your UNIX. Approved: news-answers-request@MIT.Edu Lines: 2088 Xref: umd5.umd.edu comp.unix.sys5.r4:4439 comp.unix.pc-clone.32bit:4607 comp.sys.intel:8761 comp.os.linux.announce:1007 news.answers:11185 Archive-name: pc-unix/hardware Last-update: 05 Aug 1993 Supersedes: <1mMD4G#M3Nw5X03ryhMX4Bp3Fl77S7Mf=esr@boojum.thyrsus.com> Version: 17.0 [This is a reposting. Due to a script error, the 17.0 FAQ was previously posted with a bad Expires header.] Many FAQs, including this one, are available via FTP on the archive site rtfm.mit.edu (alias rtfm.mit.edu or 18.172.1.27) in the directory pub/usenet/news.answers. The name under which this FAQ is archived appears in the Archive-name line above. This FAQ is updated monthly; if you want the latest version, please query the archive rather than emailing the overworked maintainer. What's new in this issue: * Some neon for Swan Technologies. * Updated MetroLink pricing, more about SGCS. Gentle Reader: if you end up buying something based on information from this Guide, please do yourself and the net a favor; make a point of telling the vendor "Eric's FAQ sent me" or some equivalent. The idea isn't to hype me personally, I've already got all the notoriety I need from doing things like _The_New_Hacker's_Dictionary_ --- but if we can show vendors that the Guide influences a lot of purchasing decisions, I can be a more effective advocate for the net's interests, and for you. 0. Contents I. Introduction II. Overview of the Market III. Buying the basics A. Getting Down to Cases B. Power Supplies and Fans C. The Heart Of The Machine D. Motherboards and BIOSes E. Memory F. Peripherals G. Monitors and Video Cards H. Keyboards I. Power Protection J. Radio Frequency Interference IV. Performance tuning A. How To Pick Your Processor B. Of Memory In... C. Cache Flow D. Bus Wars E. IDE vs. SCSI F. Other Disk Decisions G. Souping Up X Performance V. Hardware for Backups A. Which Technology to Choose B. Overview of QIC Devices C. Hints and Tips on Buying Tape Drives VI. Of Mice and Machines VII. Multimedia Hardware and Other Frills A. CD-ROM Drives B. Sound Cards and Speakers VIII. Special considerations when buying laptops IX. When, Where and How to Buy X. Questions You Should Always Ask Your Vendor A. Minimum Warranty Provisions B. Documentation C. A System Quality Checklist XI. Things to Check when Buying Mail-Order A. Tricks and Traps in Mail-Order Warranties B. Special Questions to Ask Mail-Order Vendors Before Buying C. Payment Method XII. Which Clone Vendors to Talk To I. Introduction The purpose of this posting is to give you the background information you need to be a savvy buyer of 386/486 hardware for running UNIX. It is aimed especially at hackers and others with the technical skills and confidence to go to the mail-order channel, but contains plenty of useful advice for people buying store-front retail. It was formerly part of 386-buyers-faq issues 1.0 through 4.0, and is still best read in conjunction with the pc-unix/software FAQ descended from that posting. This document is maintained and periodically updated as a service to the net by Eric S. Raymond <esr@snark.thyrsus.com>, who began it for the very best self-interested reason that he was in the market and didn't believe in plonking down several grand without doing his homework first (no, I don't get paid for this, though I have had a bunch of free software and hardware dumped on me as a result of it!). Corrections, updates, and all pertinent information are welcomed at that address. The editorial `we' reflects the generous contributions of many savvy USENETters. This posting is periodically broadcast to the USENET groups including comp.unix.pc-clone.32bit and to a list of vendor addresses. If you are a vendor representative, please check to make sure any information pertaining your company is current and correct. If it is not, please email me a correction ASAP. If you are a hardware-knowledgeable user, please send me any distillation of your experience that you think might improve this posting. II. Overview of the Market The central fact about 386/486 clone hardware that conditions every aspect of buying it is this: more than anywhere else in the industry, de-facto hardware standards have created a commodity market with low entry barriers, lots of competitive pressure, and volume high enough to amortize a *lot* of development on the cheap. The result is that this hardware gives you lots of bang-per-buck, and it's getting both cheaper and better all the time. Furthermore, margins are thin enough that vendors have to be lean, hungry, and *very* responsive to the market to survive. You can take advantage of this, but it does mean that much of the info in the rest of this document will be stale in three months and completely obsolete in six. One good general piece of advice is that you should avoid both the highest-end new-technology systems (those not yet shipping in volume) and the very cheapest systems put out by vendors competing primarily on price. The problem with the high end is that it usually carries a hefty "prestige" price premium, and may be a bit less reliable on average because the technology hasn't been through a lot of test/improve cycles. The problem with the low end is that price-cutters sometimes settle for marginal components. UNIX is more sensitive to hardware flakiness than DOS, so cut-price systems that might deliver consistently for DOS lemmings can come around and bite you. Use a little care, and spend the $200-$300 to stay out of the basement. It's worth it. The last point deserves a little amplification. In the PC world, there's a lot of "if it doesn't fail, it's OK". It is common to ignore normal engineering tolerances --- the allowances for variations in components, temperature, voltage margins, and the like --- and to assume that anything which doesn't fail outright must work. Watch out! For example, the ISA bus was originally designed for 6 MHz. IBM later updated that to 8 MHz, and that's as much of a standard as there is, yet there are motherboards that will let you (try to!) run it at 12 MHz --- 50% over spec. Some cards are actually designed to work at that speed with proper tolerances. Others might work...or they might flake out when they get warm. Any systems vendor above the fly-by-night level is going to shoot for a little more reliability than this, burning in systems and (often) doing at least a token system test with some kind of UNIX (usually XENIX). Pay the few extra bucks it costs to deal with a more careful vendor. The happy bottom line is this: at July 1993 direct-mail prices, you can expect to get a 486DX/33 ISA system with 8MB of memory, 240meg IDE hard disk, 3.5 and 5.25 floppies, 101-key keyboard, SuperVGA-compatible monitor and a decent no-name video card for $1500 or less. This is quite a reasonable UNIX and X machine --- and prices are dropping fast. III. Buying the basics In this section, we cover things to look out for that are more or less independent of price-performance tradeoffs, part of your minimum system for running UNIX. A. Getting Down to Cases Cases are just bent metal. It doesn't much matter who makes those, as long as they're above an easy minimum quality (on some *really* cheap ones, cards fail to line up nicely with the slots, drive bays don't align with the access cutouts, or the motherboard is ill-supported and can ground out against the chassis). If you're fussy about RFI (Radio-Frequency Interference), it's worth finding out whether the plastic parts of the case have conductive coating on the inside; that will cut down emissions significantly, but a few cheap cases omit it. Should you buy a desktop or tower case? Our advice is go with tower unless you're building a no-expansions personal system and expect to be using the floppies a lot. Many vendors charge nothing extra for a tower case and the absolute *maximum* premium I've seen is $100. What you get for that is less desktop clutter, more and bigger bays for expansion, and often (perhaps most importantly) a beefed-up power-supply and fan. Putting the box and its fan under a table is good for maybe 5db off the effective noise level, too. Airflow is also an issue; if the peripheral bays are less cramped, you get better cooling. Be prepared to buy extension cables for your keyboard and monitor, though; vendors almost never include enough flex. The airflow thing is a good argument for a full tower rather than the `baby tower' cases some vendors offer. However, baby towers are getting more attractive as boards and devices shrink and more functions migrate onto the motherboard. A state of the art system, with all 3" disks, 200W power supply, half-size motherboard, on-board IDE and 64meg of RAM sockets, and half-sized expansion cards, will fit into a baby tower with ample room for expansion; and the whole thing will fit *under* a desk and make less noise than a classic tower. For users with really heavy expansibility requirements, rackmount PC cases do exist (ask prospective vendors). Typically a rackmount case will have pretty much the same functionality as an ordinary PC case. But, you can then buy drive racks (complete with power supply), etc. to expand into. Also, you can buy passive backplanes with up to 20 or so slots. You can either put a CPU card in one of the slots, or connect it to an ordinary motherboard through one of the slots. B. Power Supplies and Fans Power supplies can matter but quality is cheap; give preference to those with a Underwriter's Laboratories rating. There's some controversy over optimum wattage level; on the one hand, you want enough wattage for expansion. On the other, big supplies are noisier, and if you draw *too little* current for the rating the delivered voltage can become unstable. And the expected wattage load from peripherals is dropping steadily. The big old 300-watt supplies that were designed for running several full-height 5.25" floppies and hard disks are overkill in these days of portable-ready lightweight 3.5" drives. 200 watts is good enough these days, and the new breed of compact 200W supplies is quieter to boot. About that annoying fan noise, ask if the power-supply fan on a target system has a variable speed motor with thermostatic control --- this will cut down on noise tremendously. If not: I have seen a rave about, but haven't used, a thermostatic fan controller called "The Silencer". This tiny device mounts inside your power supply and connects to the fan's power leads. It automatically varies the fan motor speed to hold a 79 to 82F temperature. The basic model is: $49.95 + $4.95 (S&H). For details, write: Quiet Technology Inc. 500 Executive Center - Suite 3C P.O. Box 18216 West Palm Beach, FL 33416 407-683-6200 1-800-SILENCE Warning: installing this may void your warranty! Also, be aware that a thermostatic sensor basically measures the temperature *at the sensor* (typically within the power supply box) and makes sure there is enough airflow to keep the power supply from overheating. However, the sensor does not know a thing about the temperature in certain hot spots likely to develop in a PC case (CPU, between SIMMs, between drives mounted in vertically adjacent bays). This can be a problem, because in garden variety tower cases there often isn't enough airflow to cool all components effectively even if a single is going at full speed. This is especially true if your computer has lots of add-on cards or hard disks (not much airflow between cards or between drives). Note that the fan in the power supply was basically designed to cool the power supply, not the components in the case. Not providing additional fans is a case of cheap engineering. On PCs with "expensive" engineering (e.g. HP Vectra, Compaq) one will find one to two extra fans besides the one in the power supply. So the bottom line is, use thermostatic controls if you can to cut noise. But if you want high reliability, use two or more fans. The noise produced by a fan is not just a function of the speed with which it turns. It also depends on the nature of the airflow produced by the fan blades and the bearings of the rotor. If the blades causes lots of turbulent airflow, the fan produces lots of noise. One brand of fans that, I'm told, has a reputation for being much more silent than others even if going at full throttle is the German manufacturer Pabst. Their fans offered in US computer magazines. C. The Heart Of The Machine The 386 is now stone dead in desktop systems. Prices for 486 motherboards have dropped to the point that one needn't consider anything less than a 486DX/33, which has enough power to make a good personal UNIX box. This is your floor; how far above it you want to buy depends on your budget and job mix. We'll have much more to say about this in the section on performance tuning. D. Motherboards and BIOSes Provided you exercise a little prudence and stay out of the price basement, motherboards and BIOS chips don't vary much in quality either. There are only six or so major brands of motherboard inside all those cases and they're pretty much interchangeable; brand premiums are low to nonexistent and cost is strictly tied to maximum speed and bus type. Unless you're buying from a "name" outfit like Compaq, Dell, or AST that rolls its own motherboards and BIOSes, there are only four major brands of BIOS chip (AMI, Phoenix, Mylex, Award) and not much to choose between 'em but the look of the self-test screens. One advantage UNIX buyers have is that UNIXes are built not to rely on the BIOS code (because it can't be used in protected mode without more pain than than it's worth). If your BIOS will boot properly, you're usually going to be OK. If the above sounds too rosy, there is a catch; it describes *current* hardware, not some of the historical botches. And it's hard to know how old what you're buying is. You might actually be buying a motherboard that's been sitting on the dealer's back shelf for a year, with a BIOS chip in it that was in the drawer for another year before he ever stuck it in the board. And some of those older BIOSes and board designs are to be desperately avoided. There have been quite a few bogus cache designs that either don't work at all (instant panic under UNIX) or that severely degrade performance. A lot of earlier designs have bus timing problems that show up in bad interactions with host adapters and fancy graphics boards. Bad memory designs were also not uncommon. A good, tricky way to keep the vendor from shipping you these fossils is to specify a motherboard that can take 4 or 16MB SIMMs (as opposed to just the older 1MB kind). You want to do this anyhow for functional reasons. There are a few other potential gotchas to beware of, especially in the cheaper off-brand boards. One is "shadow RAM", a trick some boards use for speeding up DOS by copying the ROM contents into RAM at startup. It should be possible to disable this. Also, on a cacheing motherboard, you need to be able to disable cacheing in the memory areas used by expansion cards. Some cheap motherboards fail to pass bus-mastering tests and so are useless for use with a good SCSI interface; on others, the bus gets flaky when its turbo (high-speed) mode is on. Fortunately, these problems aren't common. You can avoid both dangerously fossilized hardware and these little gotchas by sticking with a system or motherboard design that's been tested with UNIX (some help with that below). Some other good features to look for in a motherboard include: * Gold-plated contacts in the expansion slots and RAM sockets. Base-metal contacts tend to grow an oxidation layer which can cause intermittent connection faults that look like bad RAM chips or boards. (This is why, if your hardware starts flaking out, one of the first things to do is jiggle or remove the boards and reseat them, and press down on the RAM chips to reseat them as well -- this may break up the oxidation layer. If this doesn't work, rubbing what contacts you can reach with a soft eraser is a good fast way to remove the oxidation film. Beware, some hard erasers, including many pencil erasers, can strip off the plating, too!) * Ability to go to 64MB on the motherboard (that is, without plug-in daughterboards). Most EISA boards seem to have this (the popular Mylex MAE486 board is an exception). Note: many newer EISA boards have only 8 sockets, but these handle 16MB SIMMs. * The board should be speed-rated as high as your processor, of course. It's good if it's rated higher, so upgrade to a faster processor is just a matter of dropping in the chip and a new crystal. Finally, beware the infamous FP exception bug! Some motherboards fail to handle floating point exceptions correctly; instead of generating a SIGFPE they lock up. The following fragment of C code will reproduce the problem: double d; d = 0.0; d = 1.0 / d; /* floating divide by zero should yield SIGFPE */ John R. Levine <johnl@iecc.cambridge.ma.us> explains: "The difficulty stems from the fact that there are two ways to handle floating exceptions on a 486, the right way and the PC way. What the 486 wants to do is to generate an interrupt 16 when there is a floating point error, all entirely internal to the CPU. This has been the native way to handle floating point interrupts since the 286/287. The 286/287 and 386/387 each have a dedicated ERROR pin that the FPU uses to tell the CPU that it's time for an error interrupt. Unfortunately, the 8086/8087 handled interrupts differently. The error pin on the 8087 was wired to the 8259A interrupt controller, the same interrupt controller that handled keyboard, disk, clock, etc. interrupts. The PC/AT enshrined IRQ 13 as the one for floating interrupts. (The details of this are a little hazy to me, since the XT didn't have IRQ 13 tied to an 8259A, so the AT must have at least changed the interrupt number.) PC designs have generally wired the 287 or 387 ERROR pin to the 8259A, not to the ERROR pin on the CPU, or at best had some poorly documented way to switch between the two interrupt methods. In the interest of backward compatibility, the 486 has a mode bit that says not to handle FP exceptions automatically, but rather to freeze the FPU and send a signal on the FERR pin, which is usually tied to an 8259A which then feeds the interrupt back as IRQ 13. There is some extra complication involved here because the FPU has to stay frozen until the interrupt is accepted so the CPU can go back and look at the FPU's state. Early 386/25 chips had a bug that would sometimes freeze up on a floating point interrupt and you had to get a kludge socket with a PAL that fixed the timing glitch that provoked the bug. So as likely as not, the motherboard hardware that runs FERR out and back isn't working correctly. It's not surprising, few DOS users take floating point seriously enough to notice whether the interrupts are working right." When you specify a system, make clear to your vendor that the motherboard must handle float exceptions properly. Test your motherboard's handling of divide-by-zero; if it doesn't work, press your vendor to replace it *and send me email*! Only by publishing a list of boards known bad can we protect ourselves and pressure vendors to fix this problem. Norbert Juffa <s_juffa@iravcl.ira.uka.de> adds: Actually, the IBM PC,PC/XT and most compatible use the NMI (non-maskable interrupt) to report coprocessor errors. They don't go through the interrupt controller. Only a few not quite compatible machines did use the 8259 PIC and one needed special startup code for Microsoft-C for example to ensure correct handling of coprocessor interrupts in programs. The PC/AT and compatibles do use the 8259, and the coprocessor interrupt comes in as INT 75h (IRQs from second [slave] 8259 are mapped to INT 70h-77h) to the CPU. On the PC/XT it comes in as INT 2 (NMI). The problem with using the NMI was that NMI is also used for other purposes (e.g. parity error reporting) and that the service routine has to figure out what really caused the interrupt. The reason not to use the 8259 on the PC might have been that not enough IRQs were available. The AT has two cascaded 8259 chips and therefore has more IRQs available. The 386 UNIX Buyer's Guide posting (pc-unix/software) includes tables of motherboards and systems known to run with various UNIX ports. David E. Wexelblat <dwex@att.com> reports that, as of early 1993, Mylex EISA motherboards have some serious compatibility problems (including with some of Mylex's own peripheral cards) and should be avoided. Bill Reynolds <bill@goshawk.lanl.gov> recommends that, if you're buying an EISA motherboard, you check with the vendor to make sure it does *not* use the `Hint' chipset. It isn't true EISA. A note in the back of the Hint manual admits that the Hint's DMA, interrupts and timers aren't ISA-compatible (however, Linux will run on it). Caveat emptor. E. Memory As of June 1993, standard DRAM parts are quite reliable at 60ns cycle speed. With a decent cache, this is fast enough for any processor speed below 50MHz. You can skip the rest of this section unless you've got your heart set on a full 50MHz machine --- but be sure to read the `Cache Flow' section later on. However, memory sufficiently fast and reliable for 486/50DX systems running UNIX seems to be a particular problem. The following war story by one comp.unix sysv386 regular is typical: "Dell 2.2 ran perfectly on 3 different AMI 486/50 EISA boards. That is, after I replaced faulty memory chips which caused repeated panics. My conclusion, after consulting with our hardware suppliers, was that current quality control on top-end memory chips (NEC, Toshiba) is not good enough for 486/50s running serious Unix. The memory will pass every DOS-based test. One has to plug and play to get a set of simms that work reliably. Part of the hazerds of leading edge technology." F. Peripherals Peripherals are another matter, especially hard disks. A good rule of thumb for balanced configurations is that the hard disk should comprise about half (or maybe a bit more) of the total system hardware price (exception: if you're buying a really good monitor, like 16" or over, it's going to be expensive enough to bust this rule). Unless you're the exception who has to invoke warranty due to a system arriving dead, most of what you buy from a dealer or mail-order house is their ability to surf the Winchester market, make volume buys, and burn in your disks before shipping. We'll look at disk choices in more detail later on. You'll need a monitor, of course. The next section goes into monitor options in detail. You should have a tape drive for backup. Unfortunately, the tape drive market is rather confusing. Rather than try to give a capsule summary, we give it its own section below. We'll have much more to say about price/performance tradeoffs in peripherals in the next major section, on performance tuning. G. Monitors and Video Cards. A quick review of monitor standars for ISA machines: Horizontal Vertical Name Resolution Colors Frequency Frequency Notes ----------------------------------------------------------------------------- MDA 720x350 18.43 KHz 50 Hz CGA 640x200 2 15.85 KHz 60 Hz Obsolete 320x200 4 EGA 640x350 16 21.80 KHz 60 Hz Obsolete VGA 640x480 16 31.50 KHz 60 Hz 320x200 256 VESA VGA 640x480 16 38.86 KHz 72 Hz 320x200 256 VESA SVGA 800x600 16 48.01 KHz 72 Hz 640x480 256 8514/A 1024x768 16 35.20 KHz 43.5 Hz Interlaced XGA 1024x768 256 ?? ?? IBM proprietary VESA 1024x768 1024x768 256 56.48 KHz 70 Hz The Horizontal and Vertical Frequency columns refer to the monitor scan frequencies. The vertical frequency is the monitor's flicker rate; 60Hz is minimal for ergonomic comfort, 72Hz is VESA-recommended, and 80Hz is cutting-edge. XGA is included for completeness, but is vanishingly rare in the clone market. SVGA or `Super VGA' strictly refers only to 800x600 resolution, but is widely used for 1024x768 and even 1280x1024 resolutions. Standards above 1024x768 are weak and somewhat confused, largely because VESA's efforts have been going into the forthcoming VDID standard for auto-configuring intelligent monitors. These days, most vendors bundle a 14" monitor and super-VGA card with 1024x768 resolution in with their systems. Details to watch are whether the card comes loaded with 512K or 1MB of RAM (which will affect how much of that maximum resolution and how many colors you actually get), whether the memory is dual-ported VRAM (slightly more expensive but much faster), and whether the monitor is interlaced or non-interlaced. The latter is better and should no longer cost extra; look for the abbreviation NI in the ad or quote and be suspicious if you don't see it. You should check ahead of time which Super VGA chipset the vendor normally ships. Though DOS/Windows doesn't really care, the UNIX software that uses it (most notably X servers) will definitely notice the difference. Most implementations of X servers for Intel UNIX (especially those supplied by the UNIX vendors) don't know how to use the SVGA modes of the cheapie Oak and Trident SVGA chipsets, which are the ones most often bundled with systems. The ATI VGAWonder chipset, while better supported, isn't usually bundled. Cards based on the Tseng 4000 chipsets are often bundled or available as as an extra-cost opstion (usually less than $50 above Oak or Trident), perform better, and are supported by the most implementations of Intel UNIX-based X servers. The Tseng chipset is also the one best supported by XFree86. Other things to check for: * Dot pitch of 0.28 or smaller on a 12" or 13" monitor; 0.30 is acceptable on larger ones, especially 19" to 21" screens. Dot pitch is the physical resolution of the screen's phosphor mask. Larger dot pitches mean that small fonts and graphic detais will be fuzzy. * 72Hz or better vertical scan frequency, to cut flicker. * Non-interlaced display. Interlacing cuts the required scan frequency for a given resolution in half, but makes flicker twice as bad. As a result, interlaced monitors are rapidly disappearing; don't get stuck with one. * Does it have a tilt-and-swivel base? Adequate controls, including both horizontal and vertical size and horizontal and vertical centering? A linearity control, a trapezoidal control, and a color-temperature control are all pluses; the last is particularly important if you compose graphics on screen for hardcopy from a printer. * Is it *color*? Yes, if you don't see it in the ad, ask; some lowball outfits will try to palm off so-called "black & white VGA" monitors on you. For X use, a 14", .28mm dot pit, non-interlaced 72Mhz monitor at 640x480 resolution is the bare minimum for comfortable use, and that resolution leaves you rather squeezed for screen real estate. 1024x768 is much better. If your budget will stand it at all, a 17" or 20" monitor is a good investment. A 17" monitor is minimum if you're going to go with 1280x1024 resolution. H. Keyboards It's important to get a high quality keyboard with good key feel. See the typing-injury FAQ from sci.med.occupational to see what happens if you don't. Carpal tunnel syndrome is no fun for anyone, but it hits hackers particularly hard. Don't be a victim! Hal Snyder of Mark Williams, Co. <hal@mwc.com> sent us the following caveat: "We find that about 10% of cheap no-name keyboards do not work in scan code set 3. We are interested in scan code set 3 because only there can you reprogram the keyboard on a per-key basis as to whether keys are make-only, make-break, or autorepeat. It is a big win for international support and for X." He continues: "Keytronic, Cherry, and Honeywell keyboards, as well as a large number of imports, work fine. My advice is to either by a respected brand of keyboard, or deal with a vendor who will allow you to return an incompatible keyboard without charge." Some innovative ergonomic keyboards are just now beginning to hit the market. One that looks promising to your editor (though I haven't yet used it) is the Marquardt MiniErgo MF2, from Marquardt Switches, Inc.; 2711 Route 20 East, Cazanovia NY 13035, phone (315)-655-8050; suggested list price $170, AT-compatible interface). The MF2 features a conventional QUERTY layout, but with the right and left halves split apart and rotated about 30 degrees towards each other in a shallow V shape. The theory is that being able to angle your arms inward and your elbows out produces a less stressful typing position. The MF2 has no keypad, but it does have the standard 12 function keys across the top and arrow keys at the point of the V (meant to be thumb-operated). For more details on many ergonomic keyboards and typing-injury issues in general, see Dan Wallach's FAQ on repetitive strain injuries and ergonomic input devices, published monthly in news.answers. I. Power Protection Finally, I strongly recommend that you buy a power conditioner to protect your hardware. MOV-filtered power bars make nice fuses (they're cheap to replace), but they're not enough. I've been delighted with my TrippLite 1200, which you can get for $139 or so by mail order. A fringe benefit of this little beauty is that if you accidentally pull your plug out of the wall you may find you actually have time to re-connect it before the machine notices! The technical info in the remainder of this section is edited from material supplied by David E. Wexelblat <dwex@mtgzfs3.att.com>. There are several levels of power protection available to the home computer user. I break this down into 4 levels; others may have different ways of classifying things. The levels are: 1. Surge Suppressor 2. Line Conditioners 3. Standby Power Supplies 4. Uninterruptible Power Supplies and here's what they mean: 1. Surge suppressors These are basically a fancy fuse between the source and your hardware; they clamp down spikes, but can't fill in a low voltage level or dropout. This is a bare minimum level of protection that any piece of expensive electronics should have. Note that this applies to more than just AC power; surge suppressors are available for (and should be used on) phone lines, and RS-232 and parallel connections (for use on long lines; generally not needed if the devices is colocated with the computer and all devices are protected from outside sources). Note also that *all* devices connected to your computer need to be protected; if you put a surge suppressor on your computer but not your printer, then a zap on the printer may take out the computer, too. An important fact about surge suppressors is that *they need to be replaced if they absorb a large surge*. Besides fuses, most suppressors rely on on components called Metal-Oxide Varistors (or MOVs) for spike suppression, which degrade when they take a voltage hit. The problem with cheap suppressors is that they don't tell you when the MOV is cooked, so you can end up with no spike protection and a false sense of security --- better ones have an indicator. You can buy surge suppressors at any Radio Shack; for better prices, go mail-order through Computer Shopper or some similar magazine. All of these are low-cost devices ($10-50). 2. Line Conditioners These devices filter noise out of AC lines. Noise can degrade your power supply and cause it to fail prematurely. They also protect against short voltage dropouts and include surge suppression. My Tripp-Lite 1200 is typical of the better class of line conditioners --- a box with a good big soft-iron transformer and a couple of moby capacitors in it and *no* conductive path between the in and out sides. With one of these, you can laugh at brownouts and electrical storms. Netter Trey McLendon <sci34hub!tybrin4!holli!me@uunet.UU.NET> has good things to say about Zero Surge conditioners. He says: "Our systems at work [...] have been protected for 2.5 years now through many a violent storm...one strike knocked [out] the MOV-type suppressors on a Mac dealer's training setup across the street from us. The Zero Surge just sort of buzzed when the surge came in, with no interruption whatsoever. The basic principle is this: ZS units slow down the surge with a network of passive elements and then sends it back out the neutral line, which is tied to ground _outside at the box_ by code. MOV units shunt the surge to ground _at the computer_, where it leaps across serial ports, network connections, etc. doing its deadly work." Price vary widely, from $40-400, depending on the power rating and capabilities of the device. Mail-order from a reputable supply house is your best bet. Line conditioners typically *don't* need to be replaced after a surge; check to see if yours includes MOVs. 3. Standby power supplies (SPSs) These devices are battery-based emergency power supplies that provide power for your system via an inverter if the power fails. An SPS will generally have all the capabilities of a line conditioner as well. Note: these devices do not come on line until after the power fails, and have a certain amount of delay (typically some milliseconds) before they come on line. If the capacitors in your power supply are not large enough, the SPS may not cut in in time to prevent your computer from seeing the power failure. Note also that many SPSs are marketed as Uninterruptable Power Supplies (see below). This is incorrect. Any device with a non-zero cutover time cannot be a true UPS. If the ad mentions a cutover time, it's an SPS, and not a UPS. The price range for these devices (depending largely on size and cutover time) is $200-2000. An SPS will *not* need to be replaced after absorbing a large surge. 4. Uninterruptable power supplies (UPSs) These devices provide full-time isolation from the incoming AC line through a transformer of some sort. These devices are on-line at all times, and if the AC line fails, the batteries will cut in. Your devices will see no interruption of their incoming AC. UPSs cost more, and provide more features. They are the ultimate in power protection. Many UPSs have an intelligent interface that will notify a connected device of a power failure, allowing it to shut down cleanly. UPSs also provide the capabilities of a line conditioner. The price range (for devices in the size range for a home computer) are $400-$2500. An UPS will *not* need to be replaced after absorbing a large surge. Now, given this information, how does one decide what to get? For a system that runs unattended, like most Unix systems, it is best to have a device that provides both power holdover and a power failure signal. Hence, for a Unix system, a UPS or SPS with UNIX monitoring software id the best choice. At least one vendor sells ordered-shutdown software for Unix, and it's fairly simple to write your own daemon to monitor a serial port, and send init a SIGPWR signal when it sees a powerdown notification on the port. Tripp Lite and APC (the two vendors with the lion's share of the market) have good UNIX monitoring software. The APC "Powerchute" software, for examples, allows you to monitor the SPS's internal temperature, or perform a UPS self-test, from any UNIX terminal! Many UPS/SPS signal ports work by asserting a pin, so that one could use a modem-control serial port on the PC and wire this pin to "Carrier Detect" in order to monitor it. Some, like the APC "SmartUPS" series, actually conduct a "dialog" with the host through a serial line in order to accomplish the monitor functions. Our recommendation for a production Unix environment is a configuration like the following: a) An on-line UPS or SPS for the computer system. An intelligent interface is mandatory, along with appropriate software for ordered shutdown. b) Surge suppression on all phone lines, and also on serial/parallel lines that leave the room. c) Line conditioners on any devices not connected to the UPS. If you do take a power hit, it's cheaper to replace a $50 line conditioner than a $1500 laser printer. If this is too expensive for you, then downgrade the UPS/SPS to a line conditioner like the TrippLite. But don't go without at least that. Running unprotected is false economy, because you *will* lose equipment to electrical storms --- and, Murphy's Law being what it is, you will always get hit at the worst possible time. An important question is "How do I know how big a UPS/SPS to get?" The watt rating of the UPS/SPS should be at least the sum of the peak ratings off all equipment connected to it (don't forget the console monitor). Power-supply marketroids tend to quote you capacities and formulas like "sum of VA ratings + 20%" which (surprise!) push you towards costler hardware. Ignore them. If a watt rating is not given, watts = 0.75*VAmax. One other consideration is that you typically shouldn't put a laser printer on a UPS --- toner heaters draw enough current to overload a UPS and cause a shutdown within seconds. The other thing is that you can't even put the laser printer on the same circuit with a UPS --- the heater kicks on every 20-30 seconds, and most UPSs will see the current draw as a brownout. So buy a separate line conditioner for the laser printer. Finally, read the UPS's installation manual carefully if you're going to use it with other power-protection devices. Some UPSs don't like having surge suppressors between them and the equipment. David personally recommends surge suppressors and line conditioners from Tripp-Lite (available both mail-order and retail), and UPSs from Best Power Technologies (Necedah, WI - 1-(800)-356-5737). I can enthusiastically second the TrippLite recommendation, but haven't dealt with Best Power at all. Evan Leibovich says "Add American Power Conversion to the list. They have paid good attention to the UNIX market, and have (by far) the best UNIX UPS monitoring scheme on the market. They're also widely available." There are many other vendors for all of these devices. Tripp-Lite has a whole range of products, from a $10 phone-line surge-suppressor, to line conditioners and SPSs with prces in the hundreds of dollars. They have a line of $50-80 line conditioners that are good for most peripherals (including your home stereo :->). Best Power Technologies sells two lines of UPSs in the range for home systems. The older and more expensive FERRUPS line (which is what David has) has a smart interface, and very good filtering and surge-suppression capabilities. He says "I have a 1.15kVA FERRUPS for my home system, which is overkill with my current hardware (although it rode out a 45 minute power failure with nary a whisper - no reboot). In 1990, I paid ~$1600 for this device, and that has since gone up. They also sell a newer line of Fortress UPSs. These are better suited in price for home systems. I don't know much about them, as they were not available when I bought my UPS. I expect that this is what most people will want to consider, though. In addition, Best sells Check-UPS, a software package (in source form) for monitoring the UPS and shutting it down. I have found Best to be a good company to deal with, with competent, knowledgeable sales people (who will be able to help you pick the right device), and helpful, courteous, and responsive technical support." Other things to know: A UPS should be wired directly to (or plugged directly into) the AC supply (i.e. a surge suppressor is neither required nor suggested between the wall and the UPS). In addition, a surge suppressor between the UPS and the equipment connected to it is redundant and also unnecessary. J. Radio Frequency Interference (Thanks to Robert Corbett <Robert.Corbett@Eng.Sun.COM> for contributing much of this section) Radio Frequency Interference (RFI) is a growing problem with PC-class machines. Today's processor speeds (20-50MHz) are souch that the electromagnetic noise generated by a PC's circuitry in normal operation can degrade or jam radio and TV reception in the neighborhood. Such noise is called Radio Frequency Interference (RFI). Computers, as transmitting devices, are regulated by the Federal Communications Commission (FCC). FCC regulations recognize two classes of computer: If a PC is to be used in a home or apartment, it must be certified to be FCC class B. If it is not, neighbors have a legal right to prevent its use. FCC class A equipment is allowed in industrial environments. Many systems are not FCC class B. Some manufacturers build boxes that are class B and then ship them with class A monitors or external disk drives. Even the cables can be a source of RFI. It pays to be cautious. For example, the Mag MX17F is FCC class B. There are less expensive versions of the MX17 that are not. The Mag MX17 is a great monitor (I wish I had one). It would be painful to own one and not be allowed to use it. An upgradeable system poses special problems. A system that is FCC class B with a 33 MHz CPU might not be when the CPU is upgraded to a 50 or 66 MHz CPU. Some upgrades require knockouts in the case to be removed. If a knockout is larger than whatever replaces it, RFI can leak out through the gap. Grounded metal shims can eliminate the leaks. IV. Performance tuning Here are the places where you can trade off spending against the performance level you want to buy and your expected job mix. A. How to Pick your Processor Right now, the chips to consider are the 486DX/33, the "clock-doubled" 486DX2/66, and the 486DX/50. The Pentium is *not* a viable option yet; it's only sampling now, and the chip's 64-bit data path is going to require board redesign and retooling radical enough to keep Pentium machines in the bleeding-edge, expensive-status-toy class for a good nine months at least. The following information appeared in article <13a29iINN21e@iraul1.ira.uka.de> by S_JUFFA@iravcl.ira.uka.de (|S| Norbert Juffa). It gives a good indication of the relative speeds in Intel's processor line: UNIX performance of Intel processors as given in Intel's literature Processor SPECmark SPECint SPECfp Whetstone Dhrystone Linpack Ref Rm double p. 2.1 dp MFLOPS 1) Intel 386/387-33 4.3 6.4 3.3 3290 15888 N/A 1 *+ 2) Intel 386/387-33 4.1 6.0 N/A 3200 18900 0.4 2 # 3) RapidCAD-33 6.6 7.3 6.1 5300 18275 N/A 1 *+ 4) 486DX-25 8.7 13.3 6.6 5640 32000 1.0 2 5) 486DX-33 11.1 17.5 8.2 7200 43000 1.5 3 6) 486DX-33 12.1 18.3 9.2 N/A N/A N/A 4 7) 486DX-33 14.5 19.0 12.2 12300 43500 1.6 5 & 8) 486DX-50 18.2 27.9 13.6 10710 64400 2.5 3 9) 486DX2-50 19.2 25.4 15.9 18500 63966 2.3 5 & 10)486DX-50 21.9 28.5 18.3 18500 65400 2.4 5 & 11)486DX2-66 25.6 34.0 21.2 24700 85470 3.1 5 & Remarks: * Whetstone/Dhrystone are 32-bit DOS results + SPEC ratios recomputed from SPEC timings (computed wrong in report) & note huge increase in SPEC floating point performance over previous results due to new experimental FORTRAN compiler # machine with AMD 386-40/Cyrix 83D87-40/128 kB cache is estimated by me at: 7.7 SPECint, 5.0 SPECfp, 6.1 SPECmark, 5600 double prec. Whetstones, 23000 Dhrystones, 0.6 Linpack double prec. MFlops These estimates based on my own measurements and data from: FasMath 83D87 Benchmark Report, Cyrix 1990 World's Fastest 386 40 MHz Am386(tm)DX Microprocessor Performance Summary, AMD 1991 References: 1) Intel RapidCAD(tm) Engineering CoProcessor Performance Brief. 1992 2) i486(tm) Microprocessor Performance Report. 1990. Order No. 240734-001 3) 50MHz Intel486(tm) DX Microprocessor Performance Brief. 1991. Order No. 241120-001 4) i486(tm) Microprocessor Business Performance Brief. 1990. Order No. 281352-002 5) Intel486(tm) DX2 Microprocessor Performance Brief. 1992 Order No. 241254-001 Configurations: 1) COMPAQ SystemPro 386/33 MHz, 8 MB memory, AT&T UNIX System V/386 Release 4.0 Version 2.0 2) 64 kB write back cache, AT&T UNIX System V Release 3.2CC, MetaWare High C R2.2c, SVS FORTRAN V2.8 3) COMPAQ SystemPro 386/33 MHz, 8 MB memory, AT&T UNIX System V/386 Release 4.0 Version 2.0 4) 128 kB write-back cache, 12 MB RAM, AT&T UNIX System V Release 3.2CC, MetaWare High C R2.2c, SVS FORTRAN V2.8 5) No 2nd level cache, 16 MB RAM, AT&T UNIX System V/386 R3.2, MetaWare High C R2.3p SVS FORTRAN V2.8 6) ALR PowerCache 33/4e, 128 kB cache, 16 MB RAM SCO UNIX System V R3.2.2, MetaWare High C R2.2c/R2.3k, SVS FORTRAN V 2.8 7) Intel Modular Platform, 256 kB write-back cache, 32 MB RAM, AT&T UNIX System V R4.0.4, Metaware High C R2.4b, Intel Scheduling FORTRAN 77 Compiler V0.2 8) 256 kB write-back cache (82495DX/82490DX), 16 MB RAM, AT&T UNIX System V/386 R3.2, MetaWare High C R2.3p SVS FORTRAN V2.8 9) Intel Modular Platform, 256 kB write-back cache, 32 MB RAM, AT&T UNIX System V R4.0.4, Metaware High C R2.4b, Intel Scheduling FORTRAN 77 Compiler V0.2 10)Intel Modular Platform, 256 kB write-back cache, 32 MB RAM, AT&T UNIX System V R4.0.4, Metaware High C R2.4b, Intel Scheduling FORTRAN 77 Compiler V0.2 11)Intel Modular Platform, 256 kB write-back cache, 32 MB RAM, AT&T UNIX System V R4.0.4, Metaware High C R2.4b, Intel Scheduling FORTRAN 77 Compiler V0.2 One of Intel's most recent wrinkles is the "clock-doubler" chips. The 50DX2 runs at 25MHz externally but computes at 50MHz. A 66DX2 (bus speed 33MHz) is also shipping, and there are persistent rumors of a clock-doubled 50 in the works that would compute at a blistering 100MHz! Intel likes to claim a 70% speedup for the doublers over their undoubled brethren. I've expressed skepticism about this in previous issues, but the SPECmarks above suggest that just this once the marketroids may not be lying -- much. Under UNIX, a 50DX2 is in fact nearly as fast as a true 50DX. Still, beware of anyone whose literature passes off the DX2 qualification in the fine print; they may be scamming about other things, too. Right now you'll still pay a premium for a 486/50, as that's relatively new technology and demands extra-fast memory to run full-out. Also, these processors run really hot (one correspondent described the 50 as a "toaster on a chip"). If you go this route, be sure your configuration has an extra-heavy-duty cooling fan. Or two. And, for preference, a hefty heat sink. On current trends, a 66DX2 is probably the better way to go. B. Of Memory In... Buy lots of RAM, it's the cheapest way to improve real performance on any virtual-memory system. At $30-$50 maximum per megabyte it's just plain silly to stick with the 2-4mb now standard on most clone configurations. Go to 8, you won't regret it; 16 if you're going to use X. William Davidsen <davidsen@crd.ge.com> writes: "There are two places where memory addition will show an improvement [under sar(1)], in %wio and in avwait (sar -d) on individual devices. Note that you may have to tune kernel params, some systems have a limit of 600k on i/o buffers. Also, you can hurt performance on V.3 systems with way too many buffers (like 4+MB) if you have a slow CPU." Add memory until avwait stops dropping like a rock. Above 16 is iffy on ISA boxes because the stock USL 4.0.3 kernel may try to do DMA from a location the bus can't deal with. Most UNIX vendors have fixed this by adding code that forces DMAs to take place from low memory; make absolutely sure that includes yours before you load up beyond 16MB. The pc-unix/software FAQ posting includes information on which vendors are known to have fixed this problem. Some motherboards have 16 sockets for SIMM memory modules. Some only 8. Some take only 1MB mdules, some handle 4MB. These constraints interact in funny ways. You should make sure if you are buying an entry level 2 or 6 MB system with a 16-socket motherboard that you will not have to ditch the SIMMs that are already installed in order to go to your maximum (if 16 MB is your maximum). Some systems only allow you to mix 1M and 4M SIMMs in certain combinations. Try not to get any 1M SIMMs in your initial configuration, because you'll probably end up turfing them later. That is, buy a 4MB, 8MB, 12 MB or 16MB system to start. Newer ISA designs have a 32 MB upper limit with only 8 sockets, since they can take 4Mx9s...however, this means different interleaving (only 2 banks), which limits the possible configurations. You don't want to start off with an 8 MB configuration, because that's 8 ea 1Mx9's, filling up all the sockets...the next upgrade requires replacing 1Mx9 with 4Mx9. You can't even set up 12 MB!...the first reasonable config (that won't require tossing hardware) is 16 MB, since that's one bank full of 4Mx9. Most new EISA motherboards have 64MB capacity, either as 16 4MB-capable sockets or as 8 16MB-capable sockets. C. Cache Flow The most obscure of the important factors in the performance of a UNIX 486 system is the motherboard's memory cache size and design. The two questions performance-minded buyers have to deal with are: (1) does the cache design of a given motherboard work with UNIX, and (2) how much cache SRAM should my system have? Before normal clock speeds hit two digits in MHz, cache design wasn't a big issue. But DRAM's memory-cycle times just aren't fast enough to keep up with today's processors. Thus, your machine's memory controller caches memory references in faster static RAM (SRAM), reading from main memory in chunks that the board designer hopes will be large enough to keep the CPU continuously fed under a typical job load. If the cache system fails to work, the processor will be slowed down to less than the memory's real access speed --- which, given January 1993's typical 70ns DRAM parts, is about 7MHz. The 486 includes an 8K cache right on the processor chip. If memory accesses were reliably sequential and well-localized, this would be fine. Unfortunately, one side-effect of what's today considered "good programming practice", with high-level languages using a lot of subroutine calls, is that the program counter of a typical process hops around like crazy; locality is really poor. This gives the cacheing system a workout. (UNIX makes the problem worse, because clock interrupts and other effects of multitasking design degrade locality still further). Thus, the 486's 8K internal primary cache is typically supplemented with an external caching system using SRAM to reduce the cost of an internal cache miss; in January 1993, 20ns SRAM is typical. The size and design of your motherboard cache is one of the most critical factors in your system's real performance. Unfortunately, cache design is a complicated black art, and cache performance isn't easy to predict or measure, especially under the rapidly variable system loads characteristic of UNIX. Thus, the best advice your humble editor can give is a collection of rules of thumb. Your mileage may vary... Rule 1: Buy only motherboards that have been tested with UNIX One of DOS's many sins is that it licenses poor hardware design; it's too brain-dead to stretch the cache system much. Thus, bad cache designs that will run DOS can completely hose UNIX, slowing the machine to a crawl or even (in extreme cases) causing frequent random panics. Make sure your motherboard or system has been tested with some UNIX variant. Rule 2: Be sure you get enough cache. If your motherboard offers multiple cache sizes, make sure you how much is required to service the DRAM you plan to install. Bela Lubkin writes: "Excess RAM [over what your cache can support] is a very bad idea: most designs prevent memory outside the external cache's cachable range from being cached by the 486 internal cache either. Code running from this memory runs up to 11 times slower than code running out of fully cached memory." Rule 3: "Enough cache" is at least 64K per 16MB of DRAM Hardware caches are usually designed to achieve effective 0 wait state status, rather than perform any significant buffering of data. As a general rule, 64Kb cache handles up to 16Mb memory; more is redundant. Rule 4: If possible, max out the board's cache -- it will save hassles later Bela continues: "Get the largest cache size your motherboard supports, even if you're not fully populating it with RAM. The motherboard manufacturer buys cache chips in quantity, knows how to install them correctly, and you won't end up throwing out the small chips later when you upgrade your main RAM." A lot of fast chips are held back by poor cache systems and slow memory. The 50DX has a particular problem this way, because its cycle spead is as fast as that of a 20ns cache SRAM. To avoid trouble, cloners often insert wait states at the cache, slowing down the 50DX to the effective speed of a 50DX/2. Worse than this, a lot of cloners have taken the 50DX/2 and 66DX/2 as invitations to reuse old 25- and 33MHz board designs without change. The trouble is that these chips take a double hit for each wait state, because the wait states are timed by *external* cycles. And there can be lots of them; a look at the CMOS setup screen of most 33Mhz and 50MHz system will usually reveal many wait states. [The intro to cache design has been temporarily deleted while I straighten out technical errors with several correspondents.] D. Bus wars There are three bus standards in the clone market; ISA (the original 16-bit PC/AT bus), EISA (a 32-bit bus upward-compatible from ISA), and MicroChannel, a proprietary IBM bus used in IBM's PS/2 and its few clones. Your first intelligent decision, however, is to forget MicroChannel's existence. MicroChannel is technically sweet, but PS/2 clones are rare, expensive, and doomed to stay that way by IBM's licensing terms. The action is all in the commoditized ISA and EISA market. The rest of this section used to hash over the fine points of the ISA/EISA/VESA bus wars. However, the market has recently solved that problem. The newest 486 board designs combine inexpensive EISA with one or two VESA slots for video and disk controllers. They are definitely the way to go for UNIX users. Right now, these boards are being sold in middle- to high-end machines "for the serious business user" (priced around $3.5K). It's a no-brainer to predict that they are going to get rapidly cheaper, they're going to become more widely available, and they're going to take over the market as quickly as local-bus-video designs did in '92 and early '93. Expect EISA/VESA boards to be standard on all but the lowest-end SX machines by the end of '94. The bus wars are over --- at least until Intel's Peripheral Connect Interface hits the street and goes head to head with VESA... E. IDE vs. SCSI (vs. ESDI!) Another basic decision is IDE vs. SCSI. Either kind of disk costs about the same, but the premium for a SCSI card varies all over the lot, partly because of price differences between ISA and EISA SCSI cards and especially because many motherboard vendors bundle an IDE chip right on the system board. SCSI gives you better speed and throughput and loads the processor less, a win for larger disks and an especially significant consideration in a multi-user environment; also it's more expandable. Another important win for SCSI is that it handles multiple devices much more efficiently. If you have two IDE (or ST506 or ESDI) drives, only one can transfer between memory and disk at once. In fact, you have to program them at such a low level, one drive might actually be blocked from *seeking* while you're talking to the other drive. SCSI drives are mostly autonomous and can do everything at once; and current SCSI drives are not quite fast enough to flood more than 1/2 the SCSI bus bandwidth, so you can have at least two drives on a single bus pumping full speed without using it up. In reality, you don't keep drives running full speed all the time, so you should be able to have 3-4 drives on a bus before you really start feeling bandwidth crunch. All this having been said, don't write off IDE too quickly. Sure, it's compatible with the nasty old ST506 interface, but it's *much* faster. It remains the cost-effective choice for smaller drives (up to 500MB) on systems that won't be hitting the disk constantly. Unless you're running a heavily used network or database server, don't assume SCSI will make any noticeable difference. Also, of course, IDE is cheaper. Many motherboards have IDE right on board now; if not, you'll pay maybe $15 for an IDE adapter board, as opposed to $200+ for the leading SCSI controller. Also, there are reports that the cheap SCSI cabling most vendors ship can be flaky. It's alleged that you have to use expensive high-class cables for consistently good results. If anyone out there has hard data on this, don't be shy --- I'd like to be able to confirm or deny it in a future Guide! One savvy netter observes "Don't discount ESDI, which is making a comeback. At least with ESDI the system knows what the tracks and sectors are -- the OS should know this to do good seek optimization." He goes on to observe that some ESDI drives are actually faster than SCSI. ESDI hardware is cheaper, too. Our editorial opinion is that this is probably a good idea if you're sure you're *never* going to want a tape drive --- the SCSI/ESDI price difference will get eaten if you have to buy a separate tape controller. (If you can do your own installation, I hear that used 150/250MB SCSI drives are getting quite common and cheap on the net. All 150MB QIC type drives can do 250MB on extended-length tapes, though some manufacturers discourage you from doing this to avoid excessive heade wear. But back to disks...) The following, by Ashok Singhal <ashoks@duckjibe.eng.sun.com> of Sun Microsystems with additions by your humble editor, is a valiant attempt to demystify SCSI terminology. The terms "SCSI" and "SCSI-2" refer to two different specifications. Each specification has a number of options. Many of these options are *independent* of each other. I like to think of the main options (there are others that I'll skip over because I don't know enough about them to talk about them on the net) by classifying them into five categories: 1. Logical This refers to the commands that the controllers understand. SCSI-2 defined a common command set that is pretty much a superset of the SCSI command set. Thus, you can use a SCSI-2 drive with a SCSI card (like the Adaptec 1542) but *not* vice-versa! 2. Data Width 8 bits (+ 1 parity) -> "normal" 16-bits (+ 2 parity) -> "wide" 32-bits (+ 4 parity) -> I don't know, "extra-wide??" All three options are available in SCSI-2 (yes, the draft spec I have even shows 32-bits!), although 8-bit wide is still by far the most common. SCSI-1 defined only 8-bit wide data path. 3. Electrical Interface single-ended (max cable length 6 meters) differential (max cable length 25 meters) This option is independent of options 2, 4, 5. Differential is less common but allows better noise immunity and longer cables. It's rare in SCSI-1 controls. 4. Handshake Synchronous (requests and acks alternate) Asynchronous (multiple requests can be outstanding) Both options are available for SCSI-2 (Not sure about SCSI, but I think both were available also). This is negotiated between each target and initiator; asynchronous and synchronous transfers can occur on the same bus. This is independent of 2, 3 (Not sure about 1). 5. Synchronous Speed (does not apply for asynchronous option) "Normal" is up to 5 Mtransfers/sec ( = 5MB/s for 8-bit wide, more for wider) "Fast" is up to 10 Mtransfers/s ( = 10 MB/s for 8-bit wide, more for wider) "Wide" is up to 20 Mtransfer/sec ( = 20 MB/s on 16 or 32-bit path) The fast option is defined only in SCSI-2. This options basically defines shorter timing parameters such as the assertion period and hold time. The parameters of the synchronous transfer are negotiated between each target and initiator so different speed transfers can occur over the same bus. F. Other Disk Decisions Look at seek times and transfer rates for your disk; under UNIX disk speed and throughput are so important that a 1-millisecond difference in average seek time can be noticeable. An industry insider (a man who buys hard drives for systems integration) has passed us some interesting tips about drive brands. He says the absolute best-quality drives are the Hewlett-Packards (especially the Wolverine series) but you will pay a hefty premium for that quality. The other top-tier manufacturers are Quantum and Conner; these drives combine cutting-edge technology with (especially from Conner) very aggressive pricing. The second tier consists of Maxtor, Seagate, and Western Digital. Maxtor often leads in capacity and speed, but at some cost in other quality measures. For example, many of the high-capacity Maxtor drives have serious RFI emission problems which can cause high error rates. SCSI has built-in ECC correction, so SCSI drives only take a performance hit from this; but it can lead to actual errors from IDE drives. Western Digital sells most of its output to Gateway at sweetheart prices; WD drives are thus not widely available elsewhere. Seagate is worth watching. Their past offerings have sometimes been of infamously poor quality (like the late unlamented ST225); but in 1991 they gambled their company on leapfrogging the next generation of drives, trading off a projected 18 months of losses against a shot at entering the top tier. This gamble now appears to be paying off. The newest high-capacity Seagates are very good (my friend recommends them for people looking for an upgrade in the 500meg and range). The third tier consists of Fujitsu, Micropolis, Toshiba, and everyone else (my friend observes that the Japanese are notably poor at drive manufacturing; they've never spent the money and engineering time needed to get really good at the media). Just as a matter of interest, he also says that hard drives typically start their life cycle at an OEM price around $400 each. When the price erodes to around $180, the product gets turfed --- there's no margin any more. Previous issues said "Disk cacheing is good, but there can be too much of a good thing. Excessively large caches will slow the system because the overhead for cache fills swamps the real accesses (this is especially a trap for databases and other applications that do non-sequential I/O). More than 100K of cache is probably a bad idea for a general-purpose UNIX box; watch out for manufacturers who inflate cache size because memory is cheap and they think customers will be impressed by big numbers." This may no longer be true on current hardware; in particular, most controllers will interrupt a cache-fill to fulfill a `real' read request. In any case, having a large cached hard drive (particularly in the IDEs) often does not translate to better performance. For example, Quantum makes a 210Mb IDE drive which comes with 256Kb cache. Conner and Maxtor also have 210Mb drives, but only with 64Kb caches. The transfer rate on the drives, however, show that the Quantum comes in at 890Kb/sec, while the Maxtor and Conner fly away at 1200Kb/sec. Clearly, the Conner and Maxtor make much better use of their smaller caches. Many retailers seem to enjoy advertising the "9ms" Quantum 52/80/120/200Mb drives. This speed, of course, is bogus. All the quantum drives are at least 16ms in average access. The 9ms already includes the cacheing speedup. However, it may be that *any* hardware disk cacheing is a lose for UNIX! Scott Bennett <bennett@mp.cs.niu.edu> reports a discussion on comp.unix.wizards: "nobody found the hardware disk caches to be as effective in terms of performance as the file system buffer cache...In many cases, disabling the hardware cache improved system performance substantially. The interpretation of these results was that the cacheing algorithm in the kernel was superior to, or at least better tuned to UNIX accesses than, the hardware cacheing algorithms." On the other hand, Stuart Lynne <sl@mimsey.com> writes: Ok. What I did was to use the iozone program. What this showed was that on my root disk in single user mode I could get about 500kb for writing and 1000kb for reading a 10MB file. With the disk cache disabled I was able to get the same for writing but only about 500kb for reading. I.e. it appears the cache is a win for reading, at least if you have nothing else happening. Next I used a script which started up iozone in parallel on all four disks, two to each of the big disks (three) and one on the smaller disk. A total of seven iozone's competing with each other. This showed several interesting results. First it was apparant that higher numbered drives *did* get priority on the SCSI bus. They consistantly got better throughput when competing against lower numbered drives. Specifically drive 1 got better results than drive 0 on controller 0. Drive 4 got better results than drive 3 on controller 1. All of the drives are high end Seagate and have similiar characteristics. In general with cache enabled the results where better for reading than writing. When the cache was disabled the write speed in some cases went up a bit and the read speed dropped. It would seem that the readahead in some cases can compete with the writes and slow them down. My conclusions are that we'll see better performance with the cache. First the tendency is to do more reading than writing in your average UNIX system so we probably want to optimize that. Second if we assume an adequate system cache slow writes shouldn't affect an individual process much. When we write we are filling the cache and we don't usually care how long it takes to get flushed. Of course we would notice it when writing very large files. Thus, I can only recommend experiment. Try disabling the cache. Your throughput may go up! G. Souping Up X Performance One good way to boost your X performance is to invest in a graphics card with a dedicated blitter and a high-speed local-bus connection, like the ATI 8514/A series or the S3-based Quantum, Wind/X and Orchid Fahrenheit 1280. A number of clone vendors offer these accelerator options relatively cheap and can make your X go like a banshee; however, stock X doesn't support them yet. These cards speed up X in two ways. First, they offload some common screen- painting operations from the main processor onto specialized processors on the card itself. Secondly, by using a local bus, they make it possible to send commands to the card faster than the ISA bus could allow. The combined effect can be eye-poppingly fast screen updates even at super-VGA resolutions. In general, the ATI approach (normal bus, dedicated blitter and optimization for special functions like character drawing) will speed up text display, text scrolling and window resize/move operations a lot, but line-drawing and graphics only a little. S3, on the other hand, speeds up high-bandwidth graphics drawing a lot but doesn't have as big an advantage for ordinary text operations. You pays your money and takes your choice. Benchmarks indicate that most non-CAD users are better served by the ATI approach. However, I am now using SGCS X on an S3 with a 17" monitor on a 486/50DX2 and can report that it is quite fast enough to make X pleasant to use, thank you. Opaque windows can be dragged like paper. This is *fun*! The X servers on SCO, Dell and Esix support the ATI Ultra and Fahrenheit 1280, and third-party servers for SVr4 are available from MetroLink (email sales@metrolink.com) or SGCS (info@sgcs.com). There is said to be a third vendor in this market, "Pittsburgh Powercomputing", but the name is all the info I have on them. Here is a current price list from MetroLink (orders/info at (305)-970-7353): Description Price --------------------------------------------- ------ Runtime (all servers, standard and contrib clients) 299.00 Development (full X11 and Motif 1.1.4 libraries) 299.00 Xv - Real-Time Video in an X window (true server 99.00 extension) Xie - X Imaging Extension 199.00 And here is the corresponding info from SGCS (orders/info at (800)-645-5501): Description Price --------------------------------------------- ------ Full X11R5 binaries licensed for a single CPU 295.00 ** Enhanced X11R5 source code 195.00 ** MIT source code of contributed clients 50.00 Motif binaries for a single CPU 245.00 ** X11R5 Documentation Set 150.00 ** PHIGS Documentation Set 75.00 ** DISCOUNTS: If your choose more than one selection from any of the (**) items above you will receive the following discounts: $50 off on 2 selections, $75 off on 3 selections, $100 off on 4 selections I haven't used the MetroLink product. I can personally recommend SGCS X, as I've been using it for many months now. With the exception of one bug (xconsole doesn't work) it's proved fast, featureful and reliable. And Mark Snitily has been pleasant, patient and knowledgeable in helping me deal with various configuration problems and technicalia. If you're feeling *really* flush, plump for a 15", 17" or even 20" monitor. The larger size can make a major difference in viewing comfort. Also you'll be set for VESA 1280x1024 when everybody gets to supporting that. In the mean time, the bigger screen will allow you to use fonts in smaller pixel sizes so that your text windows can be larger, giving you a substantial part of the benefit you'd get from higher pixel resolutions. If you can, buy your monitor from someplace that will let you see the same monitor (the very unit you will walk out the door with, not a different or `demo' unit of the same model) that will be on your system. There's a *lot* of quality variation even in "premium" monitor brands. The VESA (Video Electronics Standards Association) standard for local bus video connectors is now out. When you buy local-bus motherboards, insist that they be VESA-conforming. Be very clear about this and get a commitment from your vendor; some unscrupulous operations may still be attempting to unload pre-VESA motherboards on unsuspecting customers. However, beware of an associated problem. The VESA standard only recommends local bus connector speeds up to 40 mb/sec (this allegedly has to do with either holding down RFI emissions or clock skew problems; depends on who you listen to). For unbuffered designs (which most vendors prefer for performance) VESA recommends at most two expansion slots on 33MHz machines, at most one on 40MHz, and none at all sbove that speed (that is, all devices should be directly on the motherbord). They recommend a limit of 2 VESA devices at all speeds. Thus, true 50DX or higher processors (but *not* 50DX2s) may actually have to be *slowed down* to work with VESA hardware on expansion boards. The long-term solution is either hard-disk & video controllers right on the motherboard, a revised "mezzanine" VESA that decouples the local-bus signals from the CPU, or something like Intel's proposed PCI standard. In the meantime, beware of vendors purporting to sell 50MHz "VESA" mptherboards. They're not. V. Hardware for Backups A. Which Technology to Choose You should have a tape drive for backup, and because most UNIX vendors like to distribute their OS on tape. Ideally, your tape backup should be able to image your entire disk. Unfortunately, this can get quite expensive for large disks, as we'll see below. There are a bunch of non-tape niche technologies for backup, including floptical disks, Bernoulli boxes, Iomega and SyQuest removable drives, and magneto-optical drives. Ignore them all; they're half-assed attempts to combine a backup device with the fast random access needed for working storage that don't do either job very cost-effectively, especially when you consider the (high) cost of their media. Only magneto-optical drives are likely to have much of a future, and that only given improvements in access speed. (Also, a word about D/CAS: don't! Teac Digital Cassettes are small, convenient, and quiet; they come in 150 and 600meg sizes and they'll fit in a 3.5-inch bay. But they're also a single-source technology, accordingly quite expensive for their performance, and likely to stay that way. They're popular in the Mac world, which is accustomed to being jerked around by single-source suppliers, but most clone vendors won't touch them. You shouldn't either.) There are two major technologies in today's desktop tape drive market; QIC (Quarter Inch Cartridge) at the low end and midrange, and DAT (Digital Audio Tape) at the high end. The dividing line is about 1GB capacity. QIC itself comes in two flavors, DC600 cartridge and DC2000 mini-cartridge. DAT is a new technology; it's not far down its price curve yet, but clearly where the future is. DAT drive capacities are quoted in *gigabytes* (that is, thousands of megabytes). At the *very* high end, 8mm helical-scan tape (the stuff used in Sony camcorders) is beginning to compete with DAT. This is also a single-source tchnology, from Exabyte. Capacities are 2.2 and 5 gig, transfer speeds up around 500Kbytes/sec. However, QIC remains the workhorse of the backup market, and is almost certainly what you want in your UNIX box. Tricks like data compression built into the drive and extended-length tapes have increased the capacity of QIC tapes dramatically in the last few years. Here's a quick summary of the major alternatives: Size Size Speed uncompressed compressed (mbytes) (mbytes) (Kbytes/sec) QIC mini-cartridge QIC-40 40 120 ** 30-150 QIC-80 80 250 ** 30-150 QIC cartridge QIC-150 150-250 ** 100-240 QIC-525 525 1350 100-240 DAT 60-meter 1300 2K-4K 183-366 90-meter 2000 4K-8K 183-366 ** --- using extended-length tapes In general, compression on the drive will exact some penalty in transfer speed, pulling it towards the low end of the range. Also note that QIC compression schemes aren't part of the standard, so you can usually only read compressed tapes on the same make and model of drive you made them on. B. Overview of QIC Devices Most conventional QIC drives have capacities up to 525 megabytes (a little more than half a gig). A few high-end units have 1.35GB capacity. QIC is a mature technology, but one plagued by hardware incompatibilities and driver bugs. Part of the problem is that, until recently, hard disks were small enough relative to a floppy's capacity that demand for high-volume backup technology was low in the PC world; QIC vendors tended to be small, insular, technology-driven firms relatively uninterested in standardization. As a result, understanding tape drive specifications is far from trivial. Tape drive standards are developed by Quarter Inch Cartridge Drive Standards, Inc. (805-963-3853), a consortium of drive and media vendors. They develop standards for controllers, transports, heads, and media. Some of these become ANSI standards. We'll discuss the most important ones here. Common Tape Drive Interfaces: QIC-02 --- intelligent hardware tape interface QIC-36 --- simple hardware tape interface QIC-104/11 --- SCSI-1 tape interface QIC-121 --- SCSI-2 tape interface These standards describe the drive controller. QIC-02 is presently by far the most common, and QIC-36 nearly obsolete (it was designed at a time when on-board intelligence for controllers was much more expensive than now). The SCSI standards are only rarely cited by number; usually, QIC-104 and QIC-121 devices are referred to simply as "SCSI tapes". Common Recording Formats: QIC-24 --- 9-track 60-Mbyte tape format QIC-120 --- 15-track 125-Mbyte tape format QIC-150 --- 18-track 150-Mbyte tape format QIC-525 --- 26-track 525-Mbyte tape format These standards describe the drive itself. Now, in theory, these standards are upward compatible; that is, a QIC-120 drive can read a QIC-24 tape, a QIC-150 drive can read both QIC-120s and QIC-24s, and so on. There's a potential gotcha here, though, called "media incompatibility". Thus, we also need to consider: Common media: DC600A --- for QIC-24 and QIC-120 drives DC6150 --- for QIC-150 drives DC6525 --- for QIC-525 drives These are all in the DC6000 cartridge size standard on workstations, which requires a 5.25" drive bay. The DOS world also supports a series of DC2000 "mini-cartridge" QIC media less than 3.5" wide; the most popular types are extended-length QIC-40 and QIC-80 used with data compression built into the drive. Don't get stuck with one of these if you can avoid it; their data transfer rates are horrible (30K-150K/sec, or fron 20 minutes to about 2 hours to back up a 200MB drive). By way of contrast, DC6000 QIC drives have transfer rates in the 100K-240K/sec range, with most newer drives near the upper end of that range. C. Hints and Tips on Buying Tape Drives The Wangtek 5150ES (and possibly some other 525-megabyte drives) will, according to its documentation, decode QIC-24 --- but it won't read a DC600A medium formatted to QIC-150! This is also reported of the Tandberg 3640 (QIC-120) drive. So, make sure your tape drive can read the media your OS vendor is going to ship on. QIC-24 on DC600As and QIC-150 on DC6150s are very widely used as a software distribution format in the UNIX world, and you probably want to make sure your drive can read them. 60/120MB QIC drives are fairly cheap now but larger sizes (typically 150, 250, 525 QIC tapes and 1.3gig DAT) are not. DAT drives, in particular, cost more than a grand each (however, if you have large drives the up-front cost difference can quickly get eaten up by media costs). One interesting point is that if you've gone SCSI, a 150MB QIC (comparable to the drives now popular on Suns) may well be cheaper than older 60MB technology; the win is in the controller prices, which have plummeted since QIC-24 was the cutting edge. Tape drives are easy to find and pretty safe to buy through mail order. It's also possible to buy reconditioned but warrantied used drives substantially cheaper than new. One correspondent recommended Super Technologies of Chino, CA (800 322 3999); they'll sell you a rebuilt Wangtek 150 with a 7-month warranty and a controller card for $300 and change, or a DAT drive for $800. One warning: a lot of DOS-box vendors push Colorado Memory Systems "mini-QIC" drives with jumperless cards configured at runtime by the CMS backup software. Make sure you do *not* get one of these. They're cheap, and work for DOS, but UNIX doesn't know that it has to poke controller registers to make the tape transport accessible. Besides, they *look* cheap, like they're put together out of baling wire and spit --- I wouldn't trust their long-term reliability. Another warning: The Wangtek 5150ES is incompatible w/ the Adaptec 1742 or 1740 in the EISA "enhanced" or 32 bit mode. Running the Adaptec EISA card in "standard" mode (16 bit ISA mode) is the only solution if you get stuck with a 5150ES. Your humble editor has a few battle scars from tape drive integration at this point (the rants about Wangtek and CMS drives are from personal experience). We recommend the Archive ST525, a fine fast drive that works nicely with the Adaptec 1542B, *can* read DC600A/QIC-24, and handles highest-capacity QIC-525 tapes. Note however that some versions of its documentation have a critical typo in the section on setting SCSI drive IDs; they give the ID jumpers as JP3/JP2/JP1 when they are actually JP8/JP7/JP6. If you are in any doubt about your drive or manual, call Archive tech support and check. Also, it does *not* seem to be able to read QIC-120 tapes as claimed; at least, 125MB backup tapes from my old AT&T 6386WGS are unreadable. VI. Of Mice and Machines Mice and trackballs used to be simple; now, thanks to Microsoft, they're complicated. In the beginning, there was only the Mouse Systems 3-button serial mouse; this reported status to a serial port 30 times a second using a 5-byte serial packet encoding now called "C" protocol. The Logitech Series 7 and 9 mice were Mouse Systems-compatible. All UNIXes that have any mouse support at all understand C-protocol serial mice. Then Microsoft got into the act. They designed a two-button serial mouse which reports only deltas in a three-byte packet; that is, it sends changes in button status and motion reports only when the mouse is actually moving. This is called `M' protocol. Microsoft sold a lot of mice, so Logitech switched from `C' to `M' --- but they added a third button, state changes for which show up in an optional fourth byte. Thus, `M+' protocol, upward-compatible with Microsoft's `M'. Most UNIX vendors add support for M+ mice, but it's wise to check. Bus mice are divided into 8255 and InPort types. These report info continuously at 30 or 60 Hz (though InPort mice have an option for reporting deltas only), and you get interrupts on events and then have to poll hardware ports for details. In addition to serial mice and bus mice, there are "keyboard mice". On PS/2s there are two identical-looking keyboard ports, labeled (with icons) "mouse" & "keyboard". Both are 8 or 9 pin mini-DINs that look like the regular PC keyboard port only smaller. I don't know what logical protocol the keyboard mouse speaks. Physically, the connector is eventually connected to the keyboard processor (often an 8042). The same keyboard processor that decodes the keyboard decodes the mouse. PS/2s have this port, many newer ISA/EISA motherboards do as well. All things considered, UNIX users are probably best off going with a serial mouse (most current clone motherboards give you two serial ports, so you can dedicate one to this and still have one for the all-important modem). Not only are the compatibility issues less daunting, but a serial mouse loads the multitasking system less due to interrupt frequency. Beware that most clone vendors, being DOS oriented, bundle M-type mice for which UNIX support is presently spotty, and they may not work with your X. Ignore the adspeak about dpi and pick a mouse/trackball that feels good to your hand. VII. Multimedia Hardware and Other Frills Most of the multimedia support out there right now is for Microsoft Windows. However, several small companies run by hackers are offering large archives of UNIX software --- even, in at least one case, an entire UNIX environment with development tools and X, on a CD-ROM (Yggdrasil LGX; see the Software Buyer's Guide). UNIX multimedia support probably won't be far behind. So here are some guidelines for smart buying. A. CD-ROM Drives Standard CD-ROMS hold about 650 megabytes of read-only data. UNIX support for CD-ROMs is invariably through SCSI drivers. Thus, you can ignore CD-ROMs that interface through proprietary controller cards. The Adaptec 1542 and other standard SCSI cards should control a SCSI CD-ROM just fine (in fact, many CD-ROM vendors recommend the Adaptec card). Any CD-ROM you buy should exceed the MPC (Multimedia PC) standard of a 150K/sec transfer rate. The MPC standard was written back in the days when 12Mhz 286s were considered fast machines, so it's a low-end limit now. The next level up in CD hardware standards is CD-ROM XA. So far, drives that support XA are few and expensive. It's not yet in wide use in the DOS/Windows world, and I don't know of any UNIX support for it, either in commercial or freeware code. 150K/sec is also the standard transfer rate for audio CDs. To retain compatibility with these but permit faster data access, many current drives use `multispin' technology --- they double their spindle velocity when accessing data, to achieve a 300K/sec rate. CD-ROM access times are down to about 280ms for high-end drives (to put this in perspective, it's 20 times slower than a typical hard disk, but considerably faster than a tape). Anything below 300ms is pretty good. Many CD-ROM drives use a caddy (a plastic frame into which you drop the CD before inserting both in the drive slot). Some are caddyless. The caddy has two advantages: (1) it helps protect the CD from scratches, and (2) it pre-positions the and supports the CD for the drive spindle, allowing faster controlled rotation. Consequently, most of the faster CD-ROM drives use caddies (though this is expected to change during the next year). They have the disadvantage of making CD-changing slightly more awkward. Most CD-ROMS will include a headphone jack so you can play audio CDs on them. Better-quality ones will also include two RCA jacks for use with speakers. Another feature to look for is a drive door or seal that protects the drive head from dust. CD-ROM formats are still an area of some confusion. A slight enhancement of the original "High Sierra" CD-ROM filesystem format (designed for use with DOS, and limited to DOS's 8+3 file-naming convention) has been standardized as ISO-9660; most UNIXes support read-only mounting of ISO-9660 volumes now and all will soon. There is a de-facto UNIX standard called `Rock Ridge' pioneered by the Sun User's Group shareware CD-ROMs. This is a way of putting an extra layer of indirection on an ISO-9660 layout that preserves UNIX's long dual-case filenames. Some UNIXes (notably BSDI and Yggdrasil LGX) can mount Rock Ridge filesystems. Expect to see this become more common, especially since Rock Ridge is expected to be approved as an ISO standard in 1993. More much more detail on CD-ROMs, CD-ROM standards and how to buy drives is available in the alt.cdrom FAQ, available for FTP as cdrom.com:/cdrom/faq. It is also archived in the news.answers tree at rtfm. This FAQ includes comparison tables tables of numerous drive types, CD-ROM sources, and ordering information. B. Sound Cards and Speakers Software support for driving sound cards from UNIX is, at this point, sketchy to nonexistent. Lance Norskog <thinman@netcom.com> has written a Soundblaster driver for SVr3 and SVr4. Steve Haehnichen <shaehnic@ucsd.edu> has done likewise for BSD. Linux includes drivers for other boards including the PAS Adlib. For more details, see the PCsoundboards/generic FAQ (available on rtfm in the news.answers archive). VIII. Special considerations when buying laptops Right now (March 1993) the laptop market is completely crazy. The technology is in a state of violent flux, with "standards" phasing in and out and prices dropping like rocks. We do not recommend buying a laptop until things have settled out a bit. However, if you have an immediate need for such a creature, there are a few basic things to know that will help. First: despite what you may believe, the most important aspect of any laptop is *not* the cpu, or the disk, or the memory, or the screen, or the battery capacity. It's the keyboard feel, since unlike in a PC, you cannot throw the keyboard away and replace it with another one unless you replace the whole computer. NEVER BUY ANY LAPTOP THAT YOU HAVE NOT TYPED ON FOR A COUPLE HOURS. Trying a keyboard for a few minutes is not enough. Keyboards have very subtle properties that can still affect whether they mess up your wrists. A standard desktop keyboard has keycaps 19mm across with 7.55mm between them. If you plot frequency of typing errors against keycap size, it turns out there's a sharp knee in the curve at 17.8 millimeters. Beware of "kneetop" and "palmtop" machines, which squeeze the keycaps a lot tighter and typically don't have enough oomph for UNIX anyway; you're best off with the "notebook" class machines that have full-sized keys. Second: be careful that your laptop meets the minimum core and disk requirements for the UNIX you want to run. This is generally not a problem with desktop machines, which can be upgraded cheaply and easily, but laptops often have more stringent constraints. Reject outright any machine that can't carry 8MB RAM and a 120MB fast disk. Third: with present flatscreens, 640x480 VGA color is the best you're going to do. If you want more than that (for X, for example) you have to either fall back to a desktop or make sure there's an external-monitor port on the laptop (and many laptops won't support higher resolution than the flatscreen's). Fourth: look for Nickel-Metal-Hydride (NiMH) batteries, as opposed to the older (Nickel-Cadmium) NiCad type. NiMH batteries are great because they have considerably higher energy capacity per pound that NiCads. They need special circuitry to charge them fast, so don't try to throw out your NiCads and replace them with NiMH cells if you use a fast charger intended for NiCads. Both kinds of cells can be damaged by overcharging at rates faster than 10 hours. Fifth: Most laptop electronics are still 5-volt CMOS. The coming thing is 3.3-volt CMOS with power-management features on the processor. Buy this, if you can, to nearly double your use time between recharges. Sixth: about those vendor-supplied time-between-recharge figures; DON'T BELIEVE THEM. They collect those from a totally quiescent machine, sometimes with the screen or hard disk turned off. Under DOS, you'd be lucky to get half the endurance they quote; under UNIX, which hits the disk more often, it may be less yet. Figures from magazine reviews are more reliable. One final note. Initial load of your UNIX can be a serious hurdle with laptops, as they don't tend to have on-board QICtape drives :-). The best solution is to spring for an Ethernet card on the portable and use the network-load facility supported by Dell or ESIX. Otherwise you're going to be shuffling a *lot* of 3.5" floppies. IX. When, Where and How to Buy If you're a serious UNIX hacker for either fun or profit, you're probably in the market for what the mail-order vendors think of as a high-end or even `server' configuration, and you're going to pay a bit more than the DOS lemmings. On the other hand, prices keep dropping, so there's a temptation to wait forever to buy. A tactic that makes a lot of sense in this market, if you have the leisure, is to fix in your mind a configuration and a trigger price that's just a little sweeter than the market now offers and buy when that's reached. Direct-mail buying makes a lot of sense today for anyone with more technical savvy than J. Random Luser in a suit. Even from no-name mail-order houses, parts and system quality tend to be high and consistent, so conventional dealerships don't really have much more to offer than a warm fuzzy feeling. Furthermore, competition has become so intense that even mail-order vendors today have to offer not just lower prices than ever before but warranty and support policies of a depth that would have seemed incredible a few years back. For example, many bundle a year of on-site hardware support with their medium- and high-end "business" configurations for a very low premium over the bare hardware. Note, however, that assembling a system yourself out of mail-order parts is *not* likely to save you money over dealing with the mail-order systems houses. You can't buy parts at the volume they do; the discounts they command are bigger than the premiums reflected in their prices. The lack of any system warranty or support can also be a problem even if you're expert enough to do the integration yourself --- because you also assume all the risk of defective parts and integration problems. Cruise through "Computer Shopper" and similar monthly ad compendia. Even if you decide to go with a conventional dealer, this will tell you what *their* premiums look like. You may want to subscribe to ClariNet Communications's "Street Price Report", a digest of lowest current quoted prices and sources (send inquiries to info@clarinet.com). It's $29.95 per year, so using it just once is likely to save you more money than the subscription. The Street Price Report is issued every other Thursday; you can have it emailed to you, or get it from an FTP site and decrypt it using an emailed key. It covers a wide variety of hardware and software. Quotes are collected from the ad sections of major magazines including "Computer Shopper" and "PC Magazine". Once you've cruised the magazines, you know what you want and are after the lowest price, you can nail it without fail with the Street Price Report. Another alternative to conventional dealerships (with their designer "looks", stone-ignorant sales staff, and high overheads that *you* pay for) is to go with one of the thousands of the hole-in-the-wall stores run by immigrants from the other side of the International Date Line. They're usually less ignorant and have much lower overheads; they do for you locally what a mail-order house would, that is assemble and test parts they get for you from another tier of suppliers. You won't get plush carpeting or a firm handshake from a white guy with too many teeth and an expensive watch, but then you didn't really want to pay for those anyway, right? A lot of vendors bundle DOS 5.0 and variable amounts of DOS apps with their hardware. You can tell them to lose all this cruft and they'll shave $50 or $100 off the system price. However, David Wexelblat observes "there are at least two situations in which the Unix user will need DOS available: 1) most, if not all, EISA configuration utilities run under DOS, and 2) SCSICNTL.EXE by Roy Neese is a godsend for dealing with SCSI devices on Adaptec boards." Don't forget that (most places) you can avoid sales tax by buying from an out-of-state mail-order outfit, and save yourself 6-8% depending on where you live. If you live near a state line, buying from a local outfit you can often win, quite legally, by having the stuff shipped to a friend or relative just over it. Best of all is a buddy with a state-registered dealer number; these aren't very hard to get and confer not just exemption from sales tax but (often) whopping discounts from the vendors. Hand him a dollar afterwards to make it legal. (Note: I have been advised that you shouldn't try the latter tactic in Florida -- they are notoriously tough on "resale license" holders). (Note II: The Supreme Court recently ruled that states may not tax out-of-state businesses under existing law, but left the way open for Congress to pass enabling legislation. Let's hope the mail-order industry has good lobbyists.) You can often get out of paying tax just by paying cash, especially at computer shows. You can always say you're going to ship the equipment out of the state. On the other hand, one good argument for buying locally is that you may have to pay return postage if you ship the system back. On a big, heavy system, this can make up the difference from the savings on sales tax. X. Questions You Should Always Ask Your Vendor A. Minimum Warranty Provisions The weakest guarantee you should settle for in the mail-order market should include: * 72-hour burn-in to avoid that sudden infant death syndrome. (Also, try to find out if they do a power-cycling test and how many repeats they do; this stresses the hardware much more than steady burn-in.) * 30 day money-back guarantee. Watch out for fine print that weakens this with a restocking fee or limits it with exclusions. * 1 year parts and labor guarantee (some vendors give 2 years). * 1 year of 800 number tech support (many vendors give lifetime support). Additionally, many vendors offer a year of on-site service free. You should find out who they contract the service to. Also be sure the free service coverage area includes your site; some unscrupulous vendors weasel their way out with "some locations pay extra", which translates roughly to "through the nose if you're further away than our parking lot". If you're buying store-front, find out what they'll guarantee beyond the above. If the answer is "nothing", go somewhere else. B. Documentation Ask your potential suppliers what kind and volume of documentation they supply with your hardware. You should get, at minimum, operations manuals for the motherboard and each card or peripheral; also an IRQ list, and a bad-block listing if your Winchester is ESDI rather than IDE or SCSI (the latter two types of drive do their own bad-block mapping internally). Skimpiness in this area is a valuable clue that they may be using no-name parts from Upper Baluchistan, which is not necessarily a red flag in itself but should prompt you to ask more questions. C. A System Quality Checklist There are various cost-cutting tactics a vendor can use which bring down the system's overall quality. Here are some good questions to ask: * Is the memory zero-wait-state? One or more wait states allows the vendor to use slower and cheaper memory but will slow down your actual memory subsystem throughput. This is a particularly important question for the *cache* memory! * If you're buying a factory-configured system, does it have FCC certification? While it's not necessarily the case that a non-certified system is going to spew a lot of radio-frequency interference, certification is legally required --- and becoming more important as clock frequencies climb. Lack of that sticker may indicate a fly-by-night vendor, or at least one in danger of being raided and shut down! XI. Things to Check when Buying Mail-Order A. Tricks and Traps in Mail-Order Warranties Reading mail-order warranties is an art in itself. A few tips: Beware the deadly modifier "manufacturer's" on a warranty; this means you have to go back to the equipment's original manufacturer in case of problems and can't get satisfaction from the mail-order house. Also, manufacturer's warranties run from the date *they* ship; by the time the mail-order house assembles and ships your system, it may have run out! Watch for the equally deadly "We do not guarantee compatibility". This gotcha on a component vendor's ad means you may not be able to return, say, a video card that fails to work with your motherboard. Another dangerous phrase is "We reserve the right to substitute equivalent items". This means that instead of getting the high-quality name-brand parts advertised in the configuration you just ordered, you may get those no-name parts from Upper Baluchistan --- theoretically equivalent according to the spec sheets, but perhaps more likely to die the day after the warranty expires. Substitution can be interpreted as "bait and switch", so most vendors are scared of getting called on this. Very few will hold their position if you press the matter. Another red flag: "Only warranted in supported environments". This may mean they won't honor a warranty on a non-DOS system at all, or it may mean they'll insist on installing the UNIX on disk themselves. One absolute show-stopper is the phrase "All sales are final". This means you have *no* options if a part doesn't work. Avoid any company with this policy. B. Special Questions to Ask Mail-Order Vendors Before Buying * Does the vendor have the part or system presently in stock? Mail order companies tend to run with very lean inventories; if they don't have your item in stock, delivery may take longer. Possibly *much* longer. * Does the vendor pay for shipping? What's the delivery wait? * If you need to return your system, is there a restocking fee? and will the vendor cover the return freight? Knowing the restocking fee can be particularly important, as they make keep you from getting real satisfaction on a bad major part. Avoid dealing with anyone who quotes more than a 15% restocking fee --- and it's a good idea, if possible, to avoid any dealer who charges a restocking fee at all. Warranties are tricky. There are companies whose warranties are invalidated by opening the case. Some of those companies sell upgradeable systems, but only authorized service centers can do upgrades without invalidating the warranty. Sometimes a system is purchased with the warranty already invalidated. There are vendors who buy minimal systems and upgrade them with cheap RAM and/or disk drives. If the vendor is not an authorized service center, the manufacturer's warranty is invalidated. The only recourse in case of a problem is the vendor's warranty. So beware! C. Payment Method It's a good idea to pay with AmEx or Visa or MasterCard; that way you can stop payment if you get a lemon, and may benefit from a buyer-protection plan using the credit card company's clout (not all cards offer buyer-protection plans, and some that do have restrictions which may be applicable). However, watch for phrases like "Credit card surcharges apply" or "All prices reflect 3% cash discount" which mean you're going to get socked extra if you pay by card. Note that many credit-card companies have clauses in their standard contracts forbidding such surcharges. You can (and should) report such practices to your credit-card issuer. If you already paid the surcharge, they will usually see to it that it is restituted to you. Credit-card companies will often stop dealing with businesses that repeat such behavior. XII. Which Clone Vendors to Talk To Your editor has found the folks at Swan Technologies (call 1-(800)-968-9044) to be most knowledgeable and helpful. In June 1993, a Byte Magazine report on the best machines for UNIX (page 178) rated their 486/50ES tower box first runner-up for expansibility and first runner-up for best overall. They won over CompuAdd, AST, DEC, Unisys, and NEC (the winner was an outfit called Hertz which fielded a 66MHz machine against Swan's 50). I went through the March 1992 issue of Computer Shopper calling vendor 800 numbers with the following question: "Does your company have any configurations aimed at the UNIX market; do you use UNIX in-house; do you know of any of the current 386 or 486 ports running successfully on your hardware? I didn't call vendors who didn't advertise an 800 number. This was only partly to avoid phone-bill hell; I figured that toll-free order & info numbers are so standard in this industry sector that any outfit unable or unwilling to spring for one probably couldn't meet the rest of the ante either (however, listing a *non*-800 number is a must for vendors interested in international sales, because 800 service doesn't work outside the U.S.). I also omitted parts houses with token systems offerings and anybody who wasn't selling desktops or towers with a 386/33DX or heavier processor inside. After plundering Computer Shopper, I called up a couple of "name" outfits that don't work direct-mail and got the same info from them. The answers I get revealed that for most clone vendors UNIX is barely a blip on the screen. Only a few have tested with an SVr4 port. Most seem barely aware that the market exists. Many seem to rely on their motherboard vendors to tell them what they're compatible, without actually testing whole systems. Since most compatibility problems have to do with peripheral cards, this is a problem. Here's a summary of the most positive responses I got: A --- Advertises UNIX compatibility. C --- Has known UNIX customers. I --- Uses UNIX in-house. T --- Have formally tested UNIX versions on their hardware. F --- Have 486/50 systems * --- Sounded to me like they might actually have a clue about the UNIX market. Vendor A C I T F * Ports known to work --------------- - - - - - - ----------------------------------------------- ARC . . X X . . SCO XENIX 2.3.2, SCO UNIX 3.2.1 AST . X X X X * SCO UNIX 3.2.4, ODT 2.0 Microport V/4 Allegro . . X X . . SCO XENIX 3.2.4 Altec . X . X . . XENIX (no version given). Ares . X X X X * AT&T 3.2, ISC (version unknown) Basic Time . X X X X * SCO XENIX 2.3.2, have in-house UNIX experts. Binary Tech . X . X X . Claims to work with all versions. CCSI X X . . X . They've used SCO XENIX, no version given. CIN . X . . . . SCO UNIX (version not specified) CSS . X . X . * SCO 3.2.2, ISC 3.0, SCO ODT. See Will Harper. Centrix X . . . . . No specifics on versions. Compudyne . X X X X . Couldn't get details on which versions. Comtrade . X . X X . Couldn't get details on which versions. Datom X X X X X . SCO XENIX 3.2. Dell X X X X X * See Dell SVr4 data. Desert Sands X X . X X . SCO UNIX 3.2.4 Digitech . X . X . . SCO UNIX 3.2.1, XENIX 2.3.1 EPS X X X X . * SCO XENIX 3.2.4, ISC & AT&T (versions not sp.) Gateway 2000 X X X X X * SCO UNIX 3.2.0. XENIX 2.3.4 ISC 3.0, ESIX 4.0.3 HD Computer . X . X X . SCO UNIX 3.2, SCO XENIX 3.2.2 HiQ . X . X . . SCO UNIX (version not specified) Infiniti . X . X X . SCO UNIX (versions not specified) Insight . . X . X . SCO XENIX 3.2.4. No tech support for UNIX Keydata X . X X X * SCO version 4, ISC 3.2 Legatech . X . . X . SCO UNIX, ISC (versions not specified) MicroGeneration . . X . . . Uses XENIX. MicroLab X . . . . . SCO UNIX, SCO XENIX MicroSmart X X . X . . SCO XENIX (version not specified) Microlink X . . X X . SCO XENIX (version not specified) Myoda X X . X X . SCO XENIX 3.2.2, ISC 3.2 Naga . X . X X * SCO & XENIX 3.2. Northgate X X . X X * SCO UNIX 3.2 PC Brand . X X X . . SCO XENIX, ISC UNIX PC Professional . X . X . . ISC 3.2 PC-USA X X . X . . ISC 5.3.2 and SCO 3.2 Profex . X . X . . SCO XENIX 3.2. Royal Computer . X . . X . No details on versions. SAI X X . X X . SCO UNIX 3.2.2. Santronics . . X X X . SCO XENIX 3.2.4 Solidtech . X . . . . Dell (no version given), ISC 3.2. Strobe . . . X X . SCO, Microport, ISC (no version numbers given) Swan X X X X X * SCO 2.3.1, UNIX 3.2, ISC 3.2v2.0.2 TriStar . X X X X * SCO UNIX 3.2.2, XENIX 2.3.2, ISCr4 Zenon . X . X X * SCO UNIX (version not specified) Zeos . X X X X * SCO XENIX 3.2.4, AT&T 3.2 Special notes about a few vendors who appear to have a clue: Ares targets some of its systems for UNIX CAD use. They have a house wizard name Ken Cooper (everybody calls him "K.C."). EPS targets some 486 EISA configurations for UNIX. Swan doesn't know the UNIX market very well yet, but their project manager wants a bigger piece of it and is interested in doing some of the right things. They have a house wizard, one John Buckwalter. Dell, of course, supports an industry-leading SVr4 port. They're a bit on the pricy side, but high quality and very reliable. Lots of UNIX expertise there; some of it hangs out on the net. Zeos is on the net as zeos.com, with a uunet connection; they host a UNIX BBS. They have an in-house UNIX group reachable at support@zeos.com. There are biz.zeos.general and biz.zeos.announce groups on USENET. Special notes about a lot of vendors who appear to have *no* clue: Vendors where I couldn't get a real person on the line, either because no one answered the main number or because I couldn't raise anyone at tech support after being directed there: Sunnytech, Quantex, AMS, USA Flex, Lapine, Syntax Computer, MicroTough, PAC International, The Portable Warehouse. Vendors where the question met with blank incomprehension, puzzlement, consternation, or "We've never tested with UNIX": Allur, AmtA, Aplus, HiTech, Locus Digital Products, LodeStar, Ultra-Comp, UTI Computers, PC Turbo Corp, Evertek, Microcomputer Concepts, Jinco Computers, UWE, ToughCom, System Dynamics Group, Terribly Fast Bus Systems. Vendors who understood the questions but had no answer: Bulldog Computer Products, LT Plus, Standard Computer, JCC. Vendors who said "Yes, we're UNIX-compatible" but had no details of any tests: CompuCity. Vendors who said "Go ask our motherboard vendor": Ariel Design, Lucky Computer Co., V-com, Professional Computer, MicroLine, MileHi. Vendors who sent me to a toll number: Absec, Hokkins, New Technologies, Mirage. Vendors that believe they have UNIX customers, but can't be any definite than that: Austin Computer Systems, PC Professional, Treasure Chest Computer Systems, CompuAdd Express, FastMicro, MidWest Micro. Final note: If you order from these guys, be sure to tell them you're a UNIX customer and don't need the bundled DOS. This will shave some bucks off the system price, *and* it may encourage them to pay more attention to the UNIX market. -- Send your feedback to: Eric Raymond = esr@snark.thyrsus.com |