Re: What makes a CD-ROM bootable?
- From: "robertwessel2@xxxxxxxxx" <robertwessel2@xxxxxxxxx>
- Date: Tue, 29 Jan 2008 18:17:51 -0800 (PST)
On Jan 29, 7:19 pm, Scottman <FonzoC...@xxxxxxxxx> wrote:
I am wondering what makes a CD bootable, and more specifically, if it
is possible to write some kind of boot sector that will load another
program (also on the CD-ROM) into memory and run it (all without an
OS).
Google for the "El Torito" specification. It describes basically how
a CD-ROM is made bootable. One link:
http://www.phoenix.com/NR/rdonlyres/98D3219C-9CC9-4DF5-B496-A286D893E36A/0/specscdrom.pdf
The basic idea is pretty simple. You put an image of a bootable
floppy on the CD-ROM, then there's a boot catalog file, which can
present a menu of floppy images to boot from. That's pointed to by
the boot record, which is stored in sector 17 of the last session on
the CD-ROM.
The BIOS on the PC is required to understand that structure and deal
with it. Essentially all PCs support that these days, although there
are usually some BIOS configuration options which control booting from
a CD-ROM. But in short, the PC boots from the image of the floppy on
the CD-ROM, as if it were booting from a real floppy.
The only tricks involve understanding where and when the boot floppy
image appears as a drive.
Your CD-ROM burning software will usually have an option to make a CD-
ROM bootable, and it will just need to be pointed at your floppy disk
image, and it will take care of the boot catalog and boot record.
Note that a few non-PC systems have a different way of booting from CD-
ROM.
.
- References:
- What makes a CD-ROM bootable?
- From: Scottman
- What makes a CD-ROM bootable?
- Prev by Date: Re: What makes a CD-ROM bootable?
- Next by Date: Re: Decision Tables
- Previous by thread: Re: What makes a CD-ROM bootable?
- Next by thread: general algorithm + ackermann question
- Index(es):
Relevant Pages
|
|
