funsec mailing list archives
Re: Hey old people
From: Drsolly <drsollyp () drsolly com>
Date: Wed, 21 Dec 2005 22:09:02 +0000 (GMT)
On Wed, 21 Dec 2005, Blue Boar wrote:
Drsolly wrote:The original PC Bios didn't have hard disk code, so you had to attach the HD via a device driver. That meant that you couldn't boot from the hard disk. I actually had one, it was a 10 mb monster from Xebec, costing £1000. So, since booting from a floppy was the only way to start up the computer, I wouldn't call it a vulnerability that there was no way to change that.None of them had HD BIOS code. They had hooks that would allow the add-on card to get its ROM into the POST sequence. That's what the whole Debug: G=C800:5 business to do low-level formats was about, you
I think that was particular to the WD HD controllers.
had to talk to the controller BIOS.
Maybe the original PC didn't do a rom scan?
Hm... this is hurting my brain.. I guess it was the AT that was the first machine that had HD Types, and was HD-aware?
Yes
The 5150A was missing the hook code, as well as the ability to go past 576K physical RAM.
There was a way to go past it, though. I had one of those, and I used 640kb of main memory, plus another 192kb up in rom space, used as a ramdisk.
I suppose if you want to get silly about it, I also did at least one 5150A BIOS upgrade which fixed both those problems, effectively making it a B.I actually used DOs 1.1, I don't remember whether EXEs were available or not. Are you sure they weren't? It would have meant a severe restriction on the size of programs, and I don't recollect this.I'm not 100% sure that's correct, it was a long time ago. :) Actually, I never used anything before 2.11(?) significanly myself. I used 1.0 for like 10 minutes one day, and then sold it to a collector. I thought the major features of 2.0 were heirarchical directories, upgrading from FAT10 to FAT12?, and the introduction of .exes, being the first non-directly mapped executable format for DOS, an upgrade to the old CP/M .com files. I know you couldn't really use a HD before DOS 2.0.Dos 2.0 was multiprocessing.Introduction of the TSR hooks?
Right.
It's still missing the memory protection/supervisor mode.
You couldn't do that on an 8086. _______________________________________________ Fun and Misc security discussion for OT posts. https://linuxbox.org/cgi-bin/mailman/listinfo/funsec Note: funsec is a public and open mailing list.
Current thread:
- RE: Hey old people, (continued)
- RE: Hey old people Nick FitzGerald (Dec 21)
- RE: Hey old people Jeff Rosowski (Dec 22)
- RE: Hey old people Larry Seltzer (Dec 21)
- Re[2]: Hey old people Pierre Vandevenne (Dec 21)
- Re[2]: Hey old people Drsolly (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- RE: Hey old people Drsolly (Dec 21)
- RE: Hey old people Larry Seltzer (Dec 21)
- RE: Hey old people Drsolly (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- Re: Hey old people Drsolly (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- Re: Hey old people Roland Dobbins (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- Re: Hey old people David Lodge (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- Re: Hey old people Roland Dobbins (Dec 21)
- Re: Hey old people Blue Boar (Dec 21)
- Re: Hey old people Tom Van Vleck (Dec 22)