29 Apr
2005
29 Apr
'05
8:39 p.m.
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.
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
not so much of "let's optimize what the BIOS code can do" but rather "I
need to
come up with a completely different way of doing this".
Which is what I expect a lot of people were doing in the '60s and '70s ;-)
--
Jim Leonard (trixter at oldskool.org) http://www.oldskool.org/
Want to help an ambitious games project? http://www.mobygames.com/
Or check out some trippy MindCandy at http://www.mindcandydvd.com/