Path: utzoo!attcan!uunet!dino!ux1.cso.uiuc.edu!uwm.edu!lll-winken!neoucom!wtm From: wtm@uhura.neoucom.EDU (Bill Mayhew) Newsgroups: comp.unix.i386 Subject: Re: 80386 cache and VGA Summary: AT&T Unix requies a 16 bit VGA; Unix doesn't use BIOS Message-ID: <1990Jun02.024807.724@uhura.neoucom.EDU> Date: 2 Jun 90 02:48:07 GMT Distribution: na Organization: Northeastern Ohio Universities College of Medicine Lines: 42 I know from experience that AT&T (about the same as ISC) Unix will not boot unless you have a 16 bit VGA controller and that controller is in a 16 bit slot. It'll boot from an MDA card too, of course. Cruiously, AT&T's 6386 hardware service guide shows the VGA card installed in an 8 bit slot. One of our staff people received a 6386 that had been configured by AT&T. Apparently, they must have followed the service guide. It would boot DOS, but when he tried to install the Unix bundle that came with the machine it would gag. He called, and I switched the card to a 16 bit slot, and all was fine. I can't really think of any reason why a VGA card would have problems with a cache system. I am running AT&T 3.2.1 on a JDR 33 MHz MCT board with a 64K cache and an OEM verison of the Paradise VGA Plus/16. No problems. Unix does not use the DOS BIOS for anything except to read the first level bootstrap loader from the hard drive. The reason is that DOS BIOSES use software interrupts for virtually everything. INTs aren't available in protected mode, so the results would be a real mess. The DOS BIOS also in not at all reentrant, so the kernel couldn't use the BIOS anyway. IBM is an exception. The model 80 (which the only one I have personal experience with) has a second BIOS, called, 'ABIOS' which is accessible from protected mode (A for advanced). The regular BIOS is called, 'CBIOS' (C for compatibility). The ABIOS works by calling the functions via long jumps sort of a-la CP/M, if any of you old-timers remeber that. Perhaps Xenix for PS/2s uses the ABIOS; that wouldn't surprise me too much given my experiences with SCO :-). == Bill == -- Bill Mayhew Northeastern Ohio Universities College of Medicine Rootstown, OH 44272-9995 USA 216-325-2511 wtm@uhura.neoucom.edu ....!uunet!aablue!neoucom!wtm