allred@ut-emx.UUCP (Kevin L. Allred) (07/12/89)
I recall reading some where about confilicts between the BIOS's of two 16-bit cards when using RAM shadowing. Since I'm getting a system the supports BIOS shadowing, and I may get a 16 bit VGA card and a 16 bit HD controller, I want to make sure I won't end up causing myself grief. Can anyone tell me whether there might be a problem or not? -- Kevin Allred allred@emx.cc.utexas.edu allred@ut-emx.UUCP
chasm@attctc.DALLAS.TX.US (Charles Marslett) (07/13/89)
In article <15099@ut-emx.UUCP>, allred@ut-emx.UUCP (Kevin L. Allred) writes: > I recall reading some where about confilicts between the BIOS's of two > 16-bit cards when using RAM shadowing. Since I'm getting a system the > supports BIOS shadowing, and I may get a 16 bit VGA card and a 16 bit > HD controller, I want to make sure I won't end up causing myself > grief. Can anyone tell me whether there might be a problem or not? The shadowing of the BIOS actually helps if it is done right, because the real problem arises when a 16-bit access is made to the BIOS of one card (with an 8-bit BIOS interface) and the other card jumps on the bus and tells the motherboard hardware that the addressed card is a 16-bit card (this is a lie, understandable when you look at the bus timing to do real 16-bit transfers at bus speeds greater than 6 MHz, but still a lie). If the shadowing is done by copying one byte at a time on boot up, all cards should be compatible with each other (except for the really broken ones ;^). If shadowning is done by copying one word at a time (oops!), it may make no difference, or it may exacerbate the problem. To avoid the problem entirely, just make sure that all the cards you use have either an 8-bit BIOS or a 16-bit BIOS, then it doesn't matter if the addresses get confused (when the 16-bit transfer line is yanked, that is). Here you may have a problem though -- Tseng based VGAs look like they have 16-bit BIOSes, but they don't. STB RapidMeg EMS cards can run in 8-bit, 16-bit, or dynamic modes (depending on the mother board implementation and other cards resident in the C0000-DFFFF area). Video 7 VRAM cards usually have 16-bit BIOS access, but on Everex boxes they run "fast" 8-bit accesses and occasionally crash the floppy (figure that one out!). Some 16-bit disk controllers use a BIOS, some don't, etc. The best bet is to make sure you can return anything you buy, and have a viable 8-bit and 16-bit version of each. Mix and match (you may strike it lucky, or the BIOS shadowing code may be done right) and it will work the first time! Charles Marslett > -- > > Kevin Allred > allred@emx.cc.utexas.edu > allred@ut-emx.UUCP =========================================================================== Charles Marslett STB Systems, Inc. <== Apply all standard disclaimers Wordmark Systems <== No disclaimers required -- that's just me chasm@killer.dallas.tx.us
jdm@hodge.UUCP (jdm) (07/19/89)
In article <15099@ut-emx.UUCP>, allred@ut-emx.UUCP (Kevin L. Allred) writes: > I recall reading some where about confilicts between the BIOS's of two > 16-bit cards when using RAM shadowing. I too am looking into 386 motherboards and have been asking 386 motherboard retailers about this very thing. It seems that when the problem was first discovered it happened on a wide variety of motherboards, not just on one make or model. Very quickly it was discovered that all these motherboards with the flakey Shadow RAM had one thing in common--the Phoenix BIOS. It seems the Shadow RAM is a thing implemented in the BIOS of the 386 (hence the reason why some 386 boards do not have Shadow RAM). Phoenix's version of Shadow RAM get very flakey when you have 2 or more 16-bit cards in your system each with their own BIOS (i.e. VGA and drive card). Stick to Award or Quatel BIOS. They are the only ones I have yet found that work 100% with Novell. I've fixed many a problems by replacing the AMI or Phoenix BIOS with Award. -- "I'm an anthropologist, not a computer systems architect, damit!" jdm@hodge.cts.com [uunet zardoz]!hodge!jdm James D. Murray, Ethnounixologist Hodge Computer Research Corporation 1588 North Batavia Street Orange, California 92667 USA TEL: (714) 998-7750 Ask for James FAX: (714) 921-8038 Wait for the carrier