nghiem@walt.cc.utexas.edu (Alex Nghiem) (07/16/89)
As promised, here is a summary of responses I got regarding upgrading a PC to an 80386: 1. 25 Mhz XT size (Baby AT) 80386 motherboard. Most of the 80386's given Editor's Choice by PC Magazine had AMI or AMI II BIOS. The only exceptions were Dell (custom BIOS) and Tandy (customized Phoenix BIOS.) When looking at a particular board, you must make sure it has an Intel memory cache controller. Boards with propriety design cache controllers often do not work properly with the Intel instruction set. If a board implements shadow ram BIOS (this is a function of the BIOS,) you must determine that it will not conflict with the video card that you may use. The board with shadow ram must have a way to disable the feature, if necessary. I have read that Mylex boards are NOT Xenix compatible. They appear to be priced well with a lot of nice feature, but you cannot use the board for Xenix. I received one recommendation for boards produced by Legend. I also received a comment that Micronics had the best reputation in the market for 80386 boards. Micronics also has a fairly expensive price tag at nearly two grand a piece. 2. High density 1.2 and 1.44 meg floppy drives. Got only a few responses here. Had one comment that Teac had the best reliabity in the business. Had one disgrunted comment about a Fujitsu Drive whose face plate broke while it was unpacked. Had another comment that there was no trouble read/writing 360K floppies on the Fujitsu. The general consensus of the long discussion regarding 1.2 meg/360K compatibility is that you will have no trouble mix and matching as long as the virgin disk or bulkerased disk is formatted initially to 360K format on the 1.2 meg drive. It seems to me that some drive maker should have figured out a way to make the half size 1.2 drive head format the inbetween tracks so that there would be no problem read/writing any 360K diskette. 3. 101 Keyboards I have been told to axe the Chicony keyboard. Apparently these keyboards were OEM for Everex for a while, and they were nothing but trouble. The Keytronics and Maxiswitch keyboards were recommended. The Keytronics keyboards also tend to be pricey. Any experiences with these keyboards? 4. 40 and 80 meg hard drives Apparently the Seagate ST-251-1 is a very good 40 meg design. However the ST-4096 80 meg is an older design and has a fairly large return rate. The advantage of Seagate is that it is the company that most companies have standardized on. I was recommended the Maxtor 72 meg and the Toshiba 72 meg as replacements. Any comments? 5. Hard Drive controller with floppy support. Apparently the Western Digital controller with cache is the MFM controller to get. It has a transfer rate of 5 megabit/sec and the board will fit in an XT case. I have read to avoid the Adaptec because you cannot install two of these boards in the same machine if needed. The Seagate SCSI's are very popular because they are cheap and fast. But is has been recommended that EDSI and SCSI be reserved only for drives pushing beyond 80 meg. For 80 meg or less, it is better to stick with MFM. 6. 12.5 Mhz 80286 XT (Baby AT) motherboard. The market is flooded with these boards. There is confusion about whether the Phoenix or the Award BIOS is best for this design. However, AT+T, Tandy, AST, HP, Compaq ,Western Digital, Dell and other big names at one time or another standardized on the Phoenix BIOS. Phoenix also wrote the DOS compatibility software for Sun's Sparq and 386i. Award seems to be the BIOS of choice for the underdogs. Compuadd, and a whole slew of clone makers have standardized on the Award BIOS. But other than the Compuadd machines with customized BIOS, I do no recall seeing any other Award board certified for OS/2 and Xenix. Any Comments, Inquiries? Please send E-mail. Summaries will be posted. Thanks to all who responded to inquiries regarding 80386 components. nghiem@walt.cc.utexas.edu !cs.utexas.edu!ut-emx!walt!nghiem
nghiem (Alex Nghiem) (07/23/89)
[inquiry for clarification of responses] The WD controller is the WD1006VMM2--Two floppys (all form factors) and two hd's with cache. This controller is designed for fast 286/386 machines. I had no responses regarding Microscience. I do know that the MTBF performance of Seagats drives in now advertised to be 100,000 hours. I had no comments regarding Intel manufactured mother boards. They do make an Inboard 386 and an Inboard/PC 386. I have no use for the Inboard 386, although many people are happy with them, and the Inboard/PC 386 will not do for my application because of the non-standard eight bit data path (bottleneck). The standard 386 Motherboard seems to be the Micronics 386. They have several models. They are rather pricy--from 1995 to 2095 depending on the vendor. There are several vendors in Computer Shopper who sell Micronics. As for the other manufacturers, Mylex have nice features, but do not run Xenix. There are tons of other manufacturers of other boards. Generally, the ones that sell ultra cheap have some kind of problems. I have since found that many boards with AMI bios and shadow bios do not work properly with many 16 bit video and hard disk controller cards with the shadow enabled. If you disable the shadow feature, the 384k taken up by the shadow feature is not free to be used for VDISK.SYS--you simply lose access to it. Obviously, these boards do not fit the Lotus/Intel/Microsoft standard for extended memory. So far, I have not found a cheap board that implements the disabled shadow feature properly. Right now I am trying to verify from the manufacturer of a particular board whether or not the shadow works correctly with the 16 bit bus hardware I use in the first place. That way, I won't have to worry about whether or not I will lose 384K. Problems with BIOS: I have received comments that the Phoenix 386 bios version 1.10 seems to work properly for most people with almost all software. However, there are known networking and bios shadowing problems with the Phoenix Bios that have been resolved with replacement with an Award BIOS. Award BIOS version R2 does not run Windows/386. Apparently Award R3 runs Windows nicely. Award and Quadtel bios (derived from the Award) seems to run nicely with netware. However, the Compuadd machine with the Award bios had mediocre test results. Hauppage Computer Works, on the other hand, uses the Award BIOS and are considered expensive, but very reliable. Most of the 386's reviewed by PC Magazine and given Editor's Choice had the AMI bios. PC Magazine just gave Editor's Choice to an Everex 386SX machine whose bios is derived from the AMI bios. Micronics uses the AMI bios. It seems to me that for a 386 machine, the AMI is the way to go. The problem of determining which low-cost board will work properly still remains. When looking for the board, it appears the Chips and Technology NEAT (New Extended AT) chip set is the standard. If the board uses propriety discrete logic, be wary of incompatibilites. I have not determined if the problem of losing 384k when the shadow ram is disabled is a function of the chip set or not. If it proves to be a result of the chip set, then the bug will be "standard" on lot's of clones. Regarding the Seagate SCSI drives and controllers: There were some manufacturing problems with some Seagate SCSI HD40's used by Apple, but I think they were resolved. Apple had a huge headache with the Quantum SCSI HD40's though. Any problem with Seagates are small in comparison. Many people like the ST01/ST02 controller. They are cheap and fast. There were some problems mentioned with slow transfer rates with the Seagate controllers, but I believe that they were resolved with the combination of a BIOS upgrade and documentation on how to set jumpers on the controller card for an AT (XT is the default). But, it has been reported that if the HD fails or is not recognized for any reason, the computer will not boot from a floppy--it will hang until some one corrects the hard disk problem or removes the hard disk controller card. I decided not to go with SCSI because of the lack of diagnostic software for SCSI drives on the PC--most everything currently written is for MFM ST-506 formats. I think the same deficiency holds true for EDSI and RLL formats. Of course, this lack of diagnostic software probably will change in the future. Thanks for the feedback. I really appreciate it. Send more! nghiem@walt.cc.utexas.edu !cs.utexas.edu!ut-emx!walt!nghiem