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Xref: bloom-picayune.mit.edu comp.unix.sysv386:29503 comp.sys.intel:4521 news.answers:4459 Path: bloom-picayune.mit.edu!enterpoop.mit.edu!spool.mu.edu!wupost!darwin.sura.net!jvnc.net!netnews.upenn.edu!dsinc!bagate!cbmvax!snark!esr From: esr@snark.thyrsus.com (Eric S. Raymond) Newsgroups: comp.unix.sysv386,comp.sys.intel,news.answers Subject: PC-Clone UNIX Hardware Buyer's Guide Summary: Tips on how and where to buy hardware for your UNIX. Message-ID: <1jjQh6#0364S05Wv8mS8Szh7j72XmDC=esr@snark.thyrsus.com> Date: 7 Dec 92 19:46:43 GMT Expires: 7 Mar 93 00:00:00 GMT Sender: esr@snark.thyrsus.com (Eric S. Raymond) Followup-To: comp.unix.sysv386 Lines: 1456 Approved: news-answers-request@MIT.Edu Archive-name: pc-unix/hardware Last-update: Mon Dec 7 14:40:22 1992 Version: 9.0 What's new in this issue: * A critical error in the Archive ST525 manual. * Credit-card companies often forbid card purchase surcharges. * More info about ClariNet's Street Price Report * ESDI rises from the grave. 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 powerful 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. Peripherals F. Keyboards G. Power Protection IV. Performance tuning A. How To Pick Your Processor B. Of Memory In... C. Bus Wars D. IDE vs. SCSI E. Other Disk Decisions F. Souping Up X Performance V. Tape Drive Follies VI. Of Mice and Machines VII. When, Where and How to Buy VIII. Questions You Should Always Ask Your Vendor A. Minimum Warranty Provisions B. Documentation C. A System Quality Checklist IX. 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 X. 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 group comp.unix.sysv386 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. Memory sufficiently fast and reliable for 486/50DX systems running UNIX seems to be a particular problem (anything slower than 60ns will hurt performance). 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 486/50's 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." In mid-November, one correspondent recommended Goldstar Gold-on-Gold 1x3 or 1x9. The idiots in Congress (a redundant phrase if ever there was one) have imposed an "anti-dumping" (read: "protect American fat-cats") tariff that immediately jacked up prices by $20 per megabyte. Just in time for Xmas... 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. This is a good argument for a full tower rather than the `baby tower' cases some vendors offer. Be prepared to buy extension cables for your keyboard and monitor, though; vendors almost never include enough flex. For users with really heavy expoansibility 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 pwer 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 droppong steadily. The big old 300-watt supplies that were designed for running several full-height 5.25" floppies are overkill in these days of portable-driven 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 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. Write Quiet Technology, Inc. PO Box 8478, Port St. Lucie FL 34985. Warning: installing this may void your warranty!) C. The Heart Of The Machine Yet another basic decision, of course, is processor speed and type. Until recently, the hot sellers in this market were the 386/33DX and AMD 386/40DX, which I'd say are reasonable minimum-speed engines for UNIX with X. However, recent pricing moves by Intel have moved the price of a 486SX25 below the roughly equivalent 386DX33 chip. The 386 is therefore effectively dead for new hardware, and the 486SX/25 defined as the new low end (at least for the next 90 days or so). At the system level, the current premium for 486 over 386 is about $150 as many vendors move to phase out their 386 designs. Unless you're buying a portable, we definitely recommend going 486. The 386SX machines were never a very good idea for UNIX; the 16-bit bus-to-CPU path can choke your throughput. The 486SX is even worse, a stupid marketing crock with no technical justification whatsoever. It's a 486DX with the floating-point unit missing or even deliberately lobotomized out; the difference *will* bite you in unobvious ways, for example if you use X which does a lot of FP for graphics. (One respondent opined that "SX" is Intel-internal code for "sucks".) A 486DX/33 has enough power make a good personal UNIX box. For UNIX, this is your floor; how far above them 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 interchangable; 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 4MB 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 caching motherboard, you need to be able to disable caching 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. Finally, one name-brand tip: *don't* buy DTK-brand motherboards for a UNIX system! They generate lots of spurious interrupts, which DOS is too stupid to be bothered by but which completely tank UNIX. 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). * 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. If your motherboard offers multiple cache sizes, make sure you know whether the larger cache is required when using more than a certain amount of memory. Or, in general, fill the cache all the way -- cache-speed RAM is getting pretty cheap. Note, however, that hardware caches for system boards are really designed to achieve effective 0 wait state status, rather than perform any significant buffering of data. As a general rule applicable to all clones, 64Kb cache handles up to 16Mb memory. 256Kb cache handles up to 64Mb. 128Kb cache is nearly redundant for a 16MB system; the benefit from additional caching is statistically. This means that running with 8Mb RAM, there is little difference between a 64Kb, 128Kb, or 256Kb cache on the systemboard. 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 interupt 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. The 386 UNIX Buyer's Guide posting (pc-unix/software) includes tables of motherboards and systems known to run with various UNIX ports. E. 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. 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 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. F. Keyboards 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. 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 inompatible keyboard without charge. G. 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 accidently pull your plug out of the wall you may find you actually have time to re-connect it before the machine notices! The tecbical 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. 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 of some of 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 is the best idea (an SPS is not the best power protection and most have no intelligent interface). 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 certain signal. Our recommendation for a home Unix environment is a configuration like the following: a) A true on-line UPS 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. An important question is "How do I know how big a UPS to get?" The watt rating of the UPS should be at least the sum of the peak ratings off all equipment connected to it. UPS marketroids tend to quote you UPS 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. 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, knowledgable 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. 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 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 pay as much as a $500 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. Of course, if you do this you'll be ready to drop in the rumored 100DX2 part, and blow the doors off all those fancy proprietary-technology workstations. 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. 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 EISA motherboards have 16 4MB-capable sockets, and this is clearly where the market is going. C. Bus wars Should you buy 16-bit ISA vs. 32-bit EISA? You'll pay up to a $300 premium for the latter. What you get in return is the ability to use things like fast 32-bit SCSI controllers and a smoother upward-migration path. On the other hand, EISA cards are significantly more expensive. And so far, there isn't much support for EISA-specific hardware --- a couple of vendors will drive EISA SCSI disk and tape controllers and that's about it (of course those *are* the most important bandwidth-eaters). All ISA cards will still work. Of course, most of what you get from EISA is a performance boost. There are two different theories about why EISA is better; both have their adherents. Theory A: Bandwidth matters UNIX has always been an I/O-intensive operating system. According to this theory, increasing processor speed on clones can leave it spending all its time waiting on the limited I/O capacity of the poor old 5.3MB/sec ISA bus. The vendors all seem to think this starts at around 33MHz and that if you're buying 50MHz it definitely pays to go EISA. Theory B: Cache is what matters According to this theory, UNIX never comes even close to saturating the ISA-bus bandwidth. EISA boards are faster because the premium vendors can charge for them allows the motherboard designer more freedom and a richer parts budget. The most important performance effect of this is that EISA boards have larger and better-designed caches, increasing the effective memory-access speed. There's probably some truth to both analyses. If your machine is going to spend most of its processor time running X displays and doing other classically compute-bound tasks, cache size matters most. On the other hand, benchmarks show that the combination of TCP/IP and multi-user disk activity *can* saturate ISA, and one can sometimes *see* a fast-processor machine slow down during disk accesses... If you're contemplating any kind of heavy-duty networking, EISA network adapters will become rather important. A correspondent tells me he's seen benchmarks showing what percentage of bus bandwidth is consumed by various cards when flooding an ethernet (i.e. consuming the entire 10Mbit bandwidth of a quiet net, as you might be when doing an FTP transfer, for instance). 8-bit ISA cards consume 40-60% of bus bandwidth; 16-bit cards, 20-40%. 32-bit EISA cards consume only about 5-10%. This would be particularly important in a machine being used as a bridge, where you might be handling a large portion of the traffic on two or more separate nets. The advantage of EISA cards may be due to their shorter-cycle bus mastering DMA. At time of writing, only SCO supports these, but other UNIX vendors are known to have their own drivers in the pipeline. D. 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. 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 eathen 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, 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 cammand set that is pretty much a superset of the SCSI command set. 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. Not sure, but I believe SCSI defined only 8-bit wide data path. 3. Electrical Interface single-ended (max cable length 6 meters) differential (max cable length 25 meters) Both options are available for SCSI-2 (I'm not sure about SCSI, but I think both options were available also) and this option is independent of options 2, 4, 5. Differential is less common but allows better noise immunity and longer cables. 4. Handshake Asynchronous (requests and acks alternate) Synchronous (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) 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. E. 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. Previous issues said "Disk caching 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 cache. 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 is average access. The 9ms already includes the cacheing speedup. However, it may be that *any* hardware disk caching 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 caching algorithm in the kernel was superior to, or at least better tuned to UNIX accesses than, the hardware caching algorithms." Thus, if your disk controller allows it, try disabling the cache. Your throughput may go up! F. Souping Up X Performance One good way to boost your X performance is to invest in a graphics card with a dedicated blitter or high-speed local-bus connection, like the ATI 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. SCO's X server supports 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). Here is a current price list from MetroLink: 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: Ref # Description Price ----- --------------------------------------------- ------ ** 1 Full X11R5 binaries licensed for a single CPU 295.00 ** 3 Enhanced X11R5 source code (note 4) 195.00 4 MIT source code of contributed clients (note 5) 50.00 ** 5 Motif binaries for a single CPU 245.00 ** 7 X11R5 Documentation Set 150.00 8 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 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 486/33DX2 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*! 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 (exact same, not the same monitor) 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. V. Tape Drive Follies 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 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. 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). 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 develeped 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 iomportant 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 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! 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. Your humble editor has a few battle scars from tape drive integration at this point. 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 In a previous issue, I claimed that all mice and trackballs are the same for compatibility purposes. I was wrong -- seriously wrong. The more I found out, the messier the picture gets. The following is an attempt to sort out all the confusion. Thanks to Jim McCarthy at Logitech for digging into the matter and somewhat alleviating my ignorance. 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. More on these next issue. 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-DIN's 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 motherbords 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. On the other hand: PS/2 mice deliver quadrature output (raw mouse output that all mice speak) straight to the computer. This is also how Atari and Amiga mice work. This is quite nice, because it makes the mouse simpler (and therefore more reliable), and because you only get interrupts when the mouse is actually doing something. This also means that if your PS/2 mouse breaks you can get a cheap Atari or Amiga mouse (and they *are* cheaper) to replace it without sacrificing mechanical quality (which is the important part). VII. 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 indefinately 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.) 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. VIII. 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! * Is the monitor non-interlaced? Does it have a tilt-and-swivel base? 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. What's the vertical scan rate? 60Hz is SVGA standard; 72Hz is VESA standard and minimal for flicker-free operation; 80Hz is cutting-edge. What's the dot pitch? .31mm is minimal, .28mm or .27mm is good. You need .28mm for X. A slightly larger dot pitch is acceptable in a larger monitor (16" or more). * 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! IX. 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. 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. X. Which Clone Vendors to Talk To 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. 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. Blue Dolphin . X . X X * SCO XENIX. 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; talk to Ken Germann for details. 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, TriStar Computers, 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