acero@tank.uchicago.edu (Anibal Acero) (03/07/90)
About a month ago I posted an article requesting information on 386/386sx motherboards that would allow a 287 math coprocessor on board. I also promised to summarize the responses. The responses are below. Before I get to the responses I'd like to mention two leads that I followed up which subsequently fell through. Lead 1: CompuAdd still sells a 16MHz 386 system which takes a 287, so I called them up and asked if they would sell me a motherboard. No dice. Lead 2: A company in Computer Shopper sells a 386sx motherboard which takes a 287, so I called them up. Misprint! =============Respones Summarized=============== From: wallwey@snoopy.Colorado.EDU (WALLWEY DEAN WILLIAM) To: acero@tank.uchicago.edu Subject: Re: Recommendations sought for 386sx motherboard Newsgroups: comp.sys.ibm.pc In article <7526@tank.uchicago.edu> you write: >I would like to upgrade my system as painlessly (cheaply) as possible, probably >to a 386sx motherboard. I'd like to ask the net for recommendations on a >motherboard with the following features: > > - 386sx CPU (or better) > - Accepts 80287 math coprocessor > - Permits 16-bit video I/O (compatible with ATI wonder card 512K) > - costs less than $600 > - optional, accepts 2MB add in board (EMS 4.0) > >Please mail responses to me, and I will summarized in a week to 10 days. > > >Anibal Antonio Acero acero@tank.uchicago.edu >5640 S. Ellis acero@sar2.uchicago.edu >U of Chicago, James Franck Institute >Chicago, IL 60637 (312) 702-7234 If you are considering getting a 386sx board it would probably make sense to get a mother board that can use the same memory as your add in EMS memory board and not even use the EMS board. This will allow you to take the memory off the EMS board and put it on the mother board. This will allow you to use the memory as extended memory rather than brain-dead EMS expanded memory. [if the memory is the right type and speed.] If you are worried about Applications that can only use EMS, you can use one of the powerfull Emulators that take special advantage of the 386's abilities. By using your memory this way you also use it for multitasking and other neat things....... Dean From: Mark Davis <davis@cs.unc.edu> To: acero@tank.uchicago.edu Subject: Re: Recommendations sought for 386sx motherboard Cheaper than that. The going price for 386SX motherboards is about $300. (I ordered a 386SX computer 3 days ago, so I have been watching the market.) Everyone I investigated has AMI or Phoenix BIOS, name brand (such at C &T ) chip sets and at least 6 slots with at least four 16-bit slots. Video and EMS board should be no problem. Most designs allow up to 8 Meg, but I have seen one 1 Meg board and a couple 4 Megs. All I have seen take 387SX instead of 287. I presume you want to save >> ^^^^^^ YES!!!!!! your old 287. That may not be worth it. I have seen several places selling a 386SX motherboard with 1Meg ram for $450. (Sabina 1-800-2-sabina, ) You want a name? Mylex MXS 386-26 $390, USM 1-415-623-9040, $420, EDO 1-714-8677 If you really want to spend $600, 386-20 boards go for about $650. (But then you still have to buy memory ...) Check out Computer Shopper. By the way, don't expect prices to go down anytime soon. All 386SX and 386DX are on allocation, and some clone makers have already bumped prices up a little. Hope this helps - Mark (davis@cs.unc.edu or uunet!mcnc!davis) From: ejy@honasa.att.com (Eugene Yurek) To: acero@tank.uchicago.edu Subject: Re: Recommendations sought for 386sx motherboard Hi, I have a MYLEX 386SX motherboard in a machine. I am very satisfied with it, though it fails your request in one way: uses a 387SX, not a 287. I don't know of ANY 386SX motherboards that use the 287!!! I'm not saying that there aren't any, just that I haven't come across any. The MYLEX 386SX motherboard uses SIMM 100ns. memories. To gain full-speed operation, you need 2 banks minimum (1MB with 256kx9 SIMMS or 4MB with 1Mx9 SIMMS). This is because they use a bank-interleaving technique to gain full-speed operation, as opposed to using a CACHE (I've not seen any 386SX motherboard with a cache; I think this is because a cache would add enough to the price that it would convince you to buy a full 386 motherboard). You get 8 slots on this motherboard; I think one or two are 8 bit only, and the rest are 16bit. Also, the chip-set that mylex uses to control the 386SX on the motherboard has a serial and parallel port built in. Any reputable MYLEX dealer should be able to include the necessary cables to bring these to the back of whatever case you have. This is nice because it frees a slot on the motherboard. I have 2MB on the motherboard, a Paradise 8 bit VGA+ card and Magnavox 7BM749 Monochrome VGA monitor, a Western-Digital WD1006VMM2 controller (hard/floppy 1:1 interleave) with 2 CDC 86MB hard drives and a 1.44MB floppy, an EVEREX 60MB external 5.5MB/minute tape backup unit, and soon about another 4MB of RAM on an extended memory card (I don't know from which manufacturer yet, because I'm still looking). I'm running AT&T UNIX V/386 Release 3.2.2 as well as MS-DOS 3.3 under SIMULTASK. SIMULTASK allows you to run DOS under UNIX and switch back and forth between the two (this sounds like a programmers nightmare for the people who wrote SIMULTASK, but it works fine for us users). The machine came up the first time with no problems and runs UNIX and DOS flawlessly. As for the matter of expanded memory... You don't need an EMS board with a 386 machine. An extended memory board and a program like quarterdecks QEMM-386 provide the same (and better) functionality. Remember, the reason for expanded memory was that the lowly 8086 could NOT address more than 1MB, so the inventors had to Kludge up a card that allowed it to. The 386 does not have this problem. Consequently you don't need a expanded memory Kludge card; a simple (and inexpensive) extended memory card along with a 386 expanded memory manager (like QEMM-386) gives you a lot more functionality, since all the memory mapping that an expanded memory card does is now done by the memory management unit on the 386 or 386SX. Plus, you now have additional execution memory for programs like DesqView, which, by the way, runs wonderfully on the 386. I hope these comments help a little. By no means is the MYLEX 386SX the do-all end-all 386SX motherboard. I'm just relating my experiences. By the way, I believe you can probably find the motherboard without memory with the serial/paralle cable for between $500 and $550. If you want one, and can't find it for this price, let me know and I'll give you the name and number of the place I got it from. Good Luck. -- Eugene Yurek Internet: ejy@honasa.att.com AT&T Bell Laboratories uucp: ...!att!honasa!ejy Holmdel, NJ Voice: (201) 949-3753 From: ejy@honasa.att.com (Eugene Yurek) Hi, There are some older-style 386 motherboards that still use DIP memories. I think most of these, however, don't have a cache. This means that no matter how fast your RAM is, your going to be running with several wait-states. If you decide to buy a 386 Motherboard, as opposed to a 386SX, do yourself a favor... BUY ONE WITH AN ON-BOARD CACHE You won't regret this, as the cache makes a big difference in system speed (and unfortunately, increases the price). As a small example of why you want a cache, the speed of the cache memory on even a 20MHz 386 is in the 35ns range. Just try getting DRAM that even comes close to that speed!!! I also have a plain-vanilla MS-DOS machine that is a clone I built from the ground up. It has a MYLEX MI386-20 motherboard. This is a 20MHz 386 motherboard, with a 64kb cache. A friend who has the sameA friend who has the same setup ran some benchmarks of the processor speed when running completely out of ram on the motherboard, and when running completely out of ram on a BOCARAM-AT card (150ns ram, 16 bit bus at 8MHZ) in the same machine. There was only a small difference (about 10%) in the execution times for both tests. The cache definately had an impact on the execution speed. As for motherboards that still can use the 287, I'm not sure you are going to be very successful. Most of these motherboards were introduced in the transition period around the time the 386 was announced. This was also the time when Intel hadn't yet released the 387 (or was it that they had and noone could afford it ?). Anyway, I think most of these motherboards are long gone. If you do find one, chances are that it probably won't have a cache. Caches on inexpensive motherboards have only come into vogue in the last year or so, because of the availability of relatively inexpensive fast static RAM. Sorry for taking this long to respond to your note. I came down with the FLU last sunday, and have been home since. I have to go to work this following monday, or I'm going to go nuts!!! -- Eugene J. Yurek Internet: ejy@honasa.att.com AT&T Bell Laboratories uucp: ...!att!honasa!ejy Holmdel, NJ Voice: (201) 949-3753 ==============END SUMMARY======== My sincere, whole-hearted thanks to those who responded! Epilogue: I'm still plodding along with my old braindead 286/287 12 MHz system. Anibal Antonio Acero (tony) acero@tank.uchicago.edu 5640 S. Ellis, JFI 340 University of Chicago Chicago, IL 60637 (312) 702-7234