Return to BSD News archive
Xref: sserve comp.os.linux.development:8912 comp.os.minix:23723 comp.os.mach:3800 comp.os.386bsd.development:2095 comp.sys.ibm.pc.hardware.misc:5208 Newsgroups: comp.os.linux.development,comp.os.minix,comp.os.mach,comp.os.386bsd.development,comp.sys.ibm.pc.hardware.misc Path: sserve!newshost.anu.edu.au!harbinger.cc.monash.edu.au!msuinfo!agate!howland.reston.ans.net!EU.net!sun4nl!relay.philips.nl!philica!adrie From: adrie@ica.philips.nl (Adrie Koolen) Subject: Re: Booting from CD-ROM, was: [Announcement] 386BSD Release 1.0 Message-ID: <1994May9.112318.816@ica.philips.nl> Organization: Philips Consumer Electronics, Eindhoven, The Netherlands References: <newcombe.142.00141E4A@aa.csc.peachnet.edu> <CpE8p7.H@wg.saar.de> <1994May7.211614.28288@ibr.cs.tu-bs.de> Date: Mon, 9 May 1994 11:23:18 GMT Lines: 44 In article <1994May7.211614.28288@ibr.cs.tu-bs.de> rh@ramz.ing.tu-bs.de (Ruediger Helsch) writes: >It is possible to boot from a CD-ROM. I made a CD with a boot block so >it could be bootet from a SCSI CD-ROM hanging on an AHA1542B. But >I do not know how many other SCSI adapters or CD-ROM controllers do >allow this, I think even with the AHA1542C it would not work, its BIOS >does simply refuse to boot a CD-ROM. I'm quite confused by all the messages in this thread. Some remarks: Technically, it's possible to boot from a CDROM on a PC. What's needed is a device specific BIOS on your CDROM adapter card that knows about CDROMs and how to boot from them. I thought that no SCSI controller provided support for this, but apparently the Adaptec 1542B (and 1540, as reported in an earlier message) do! But then why did Adaptec remove that feature from their 1542C BIOS? That really makes no sense!?! Well, I can think of a reason. Perhaps, the 1542B doesn't know how to handle a CDROM but just tries to read block 0. Of course, as it expects 512 bytes, but the CDROM drive tries to deliver 2048 bytes, the controller gets a Data Overrun Error (or SCSI Protocol Error, or some other error). When totally ignoring the error and just going along with the first 512 bytes, it might be able to continue the boot process. However, this would be using a bug in the 1542B's firmware! I can imagine that Adaptec removed this bug in the 1542C. I had the impression that the original poster meant to say that you could boot the CDROM on ANY CDROM drive! I didn't see a note that it was limited to a specific SCSI controller/drive type. I think that booting 386BSD from CDROM is possible with certain specific SCSI controllers (and a very limited number of them will allow it), and for those SCSI controllers (or other CDROM adapters) that don't support booting from CDROM, there will be an image of a diskette on the CDROM that you should copy to a diskette and boot from the diskette. !!! Note that I don't know this for sure. It's only my suspicion!!! Adrie Koolen (adrie@ica.philips.nl) Philips Sound and Vision, Eindhoven, the Netherlands