Does Xenix use the BIOS for anythin

[Karl Denninger]

In article <1990Mar22.172812.29265 at comm.WANG.COM> lws at comm.WANG.COM (Lyle Seaman) writes:
>
>I may have missed part of this thread, so if this doesn't make sense,
>I apologize.  
>
>If Xenix doesn't use the BIOS for anything (because the BIOS doesn't
>work w/ protected mode), then by extension, OS/2 and Unix don't use
>the BIOS either...
>
>Then howcum' I needed to upgrade my BIOS when I installed an ESDI
>controller?

The BIOS is used in a protected mode operating system only to boot the
machine.

The reason you needed to change your BIOS is that some older BIOSes didn't
correctly execute the initialization code in add-on boards.  This includes
ESDI and other controllers with an on-board BIOS... thus those controllers
would not work correctly.

ESDI, SCSI and most RLL controllers typically have an on-board BIOS that
loads the DPB block for the drives, thus "spoofing" the drive types.  In the
case of the ACB1542 SCSI adapters, it also enables redirection of the disk
I/O routines for use under MSDOS (which is needed to boot from the SCSI
devices).  If the BIOS doesn't execute these routines correctly, you get no
boot up, and thus Unix or Xenix (or OS/2) can't load.

Once the system is up, the BIOS is not used at all; it can't be since it
isn't reentrant.

--
Karl Denninger (karl at ddsw1.MCS.COM, <well-connected>!ddsw1!karl)
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