Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!cs.utexas.edu!asuvax!ncar!tank!gargoyle!ddsw1!karl From: karl@ddsw1.MCS.COM (Karl Denninger) Newsgroups: comp.unix.xenix Subject: Re: Does Xenix use the BIOS for anythin Summary: BIOS is used for booting only Message-ID: <1990Mar23.030358.3847@ddsw1.MCS.COM> Date: 23 Mar 90 03:03:58 GMT References: <115@melpar.UUCP> <286100005@trsvax> <1990Mar22.172812.29265@comm.WANG.COM> Reply-To: karl@mcs.MCS.COM (Karl Denninger) Organization: Macro Computer Solutions, Inc. - Mundelein, IL Lines: 35 In article <1990Mar22.172812.29265@comm.WANG.COM> lws@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@ddsw1.MCS.COM, !ddsw1!karl) Public Access Data Line: [+1 708 566-8911], Voice: [+1 708 566-8910] Macro Computer Solutions, Inc. "Quality Solutions at a Fair Price"