PC/Apple/etc. Cards Worth Keeping/Storing
ard at p850ug1.demon.co.uk
Sat Apr 30 16:37:37 CDT 2005
> Tony Duell wrote:
> > There was no separate TechRef for the CGA card. The hardware is covered
> > in the normal Options and Adapters Techref.
> ...which I don't have :) Oh well, hopefully there's electronic copy somewhere.
I've never seen an electronic copy of any of the Techrefs, I am not sure
if IBM would explode if somebody started distributing them, either.
> > It's supported by the
> > standard mainboard BIOS, the source lising of which is in the
> > machine-specific techrefs.
> I don't have that either, but I've disassembled my own BIOS and found that it
> is nearly useless to me -- for example, there are instructions that take longer
> to execute out of RAM (4 cycles per byte opcode) than ROM (2 cycles) -- so it's
Rememebr the true-blue IBMs didn't shaddow the ROM. The BIOS ran from ROM
all the time.
But the BIOS code is often pretty badly written. The RS232 driver in
particular is a good example of how not to do things!
To be fair, I have much the same comments about the hardware. When I got
my TechRefs, I went through all the schematics, and exclaimed at
approximately 2 minute intervals 'They did WAHT???'
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