derrick@ritcsh.csh.rit.edu (Derrick Williams) (02/14/91)
I built a Z80 cpu breadboard as described in Steve Ciarcia's "Build Your
Own Z80 computer" book, and the subproject for building a computer display
on a monitor seems to me to be rather complicated for my limited breadboarding
skills. The monitor project is for a regular composite type monitor, giving
a maximum resolution of 64 columns by 24 rows.
I have an original IBM PC monochrome monitor, one of those green ones that
the IBM originally shipped out with the 8088 based ones. Since the Z80 is
similar in terms of instruction sets, bit widths, etc to a 8088, could I
use a IBM video adaptor for my z80 breadboard project? I can get a monochrome
adaptor real cheap, and if it's an easy way out from the 33 IC project Ciarcia
outlines, I would be interested in hearing from people about the right way
to do it or any reason why I shouldn't.
I should state that I am not all that familiar with IBM PC hardware or how
video adaptors work, so I guess you all will have to spell it out for me :-) .
Thanks for any help, and I would be interested in hearing from other people
who have put together cpu breadboards, too.
Derrickwilker@descartes.math.purdue.edu (Clarence Wilkerson) (02/21/91)
The IBM displays are memory mapped. The simplest model, the monochrome TTL card, has 4k of memory, with alternating "attributes" and characters. I suspect that one could use a 8255 parallel port to simulate the PC bus well enough to drive one of these. Clarence Wilkerson