Re: Hey old people

[Blue Boar <BlueBoar () thievco com>]

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 
had to talk to the controller BIOS.

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?

The 5150A was missing the hook code, as well as the ability to go past 
576K physical RAM.

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?

It's still missing the memory protection/supervisor mode.

                                                BB
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