dasy@mitre-bedford.ARPA (David Shinberg) (07/01/88)
I have a need to purchase an EGA board for an AT Machine. It needs to be very fast as other parts of the system are slow. Additionaly it needs to support XENIX/SCO 2.2. Any suggestions or warnings will be greatly appreciated. If there is a large response I will summarize for the net. Forgive me if this is a redundant topic, but I am new to the IBM world. Thanks in Advance Dave Shinberg dasy@mitre-bedford.ARPA uunet!linus!mbunix!dasy
chasm@killer.UUCP (Charles Marslett) (07/03/88)
In article <35665@linus.UUCP>, dasy@mitre-bedford.ARPA (David Shinberg) writes: > I have a need to purchase an EGA board for an AT Machine. It needs to be > very fast as other parts of the system are slow. Additionaly it needs to > support XENIX/SCO 2.2. Any suggestions or warnings will be greatly > appreciated. If there is a large response I will summarize for the net. > Forgive me if this is a redundant topic, but I am new to the IBM world. > > Thanks in Advance > > Dave Shinberg > dasy@mitre-bedford.ARPA > uunet!linus!mbunix!dasy The question of a fast EGA/VGA card to support Xenix/Sys5/etc. has come up in personal conversations several times recently, and (to the best of my knowledge) there is not a simple answer. All (almost all?) versions of Unix and Unix clones for the 286 and 386 run in protected mode, so they have very little support from the BIOS -- this in turn means that if BIOS activity is needed to get maximum performance out of the card (if some modes can be run faster than others for example, and the speed is set with a non-standard I/O port) you get it with DOS, but not with Unix. This problem shows up mostly with the 16-bit cards because it takes a lot of hardware to speed up 8-bit transfers even to the point of matching the speed of 16-bit transfers (that is half the speed, since you need twice the number of transfers). Probably the fastest VGA card for a Unix environment is one of the Paradise cards. And the only problem I have seen with them is that (perhaps the earlier models only?) some of them fail to handle rapid updates on a 16-MHz Compaq 386 -- it may be worse on a 20 or 25 MHz box. Compaq sells a version of this card as its own, so I suspect the problem is cleared up by now (any comments from netters with Compaq VGA cards and a tendency to run animation-type code?). It is probably a lot faster than any of the EGA cards on the market, so you may want to upgrade the video sooner than you had planned -- my comparisons of the difference between this 16-bit card and all the EGA cards in my test collection show it to be about twice as fast doing EGA graphics and three to four times as fast doing text manipulation or CGA graphics (where it can use the 16-bit interface). On the other hand, I have yet to see an 8-bit EGA (or VGA) that would not run on virtually any machine (up to 16-MHz 286s and 20-MHz 386s). I think this is a result of having the motherboard assume immense numbers of wait states for byte transfers (my compaq will use 17-25 when accessing any of the 8-bit boards I test with, while the Paradise board runs with either 12 or 14). Any Help? Charles Marslett chasm@killer.UUCP ...!ihnp4!killer!chasm