You're right. The "text" mode was really not a valid construct for VGA
monitors. Many EGA monitors would work just as well as VGA's, which, I
guess is a testament to the not so unusual notion that people charge less
for a product even though they've spend extra resources to make it less
valuable. The "hardware" text mode with which I'm familiar is simply a
color killer, which drives the display into a light green on a dark green
background. It didn't do anything to the sync. Monitors which work with
VGA should be fine. What's required in order to make the VGA look like
monochrome, is either to drive all the colors equally or to drive only the
green video. It would be much simpler to allow the use of an S-100 adapter
to use his old monochrome monitor with either a mono or a Hercules, or
whatever other card he desires. His software will have to deal with it
anyway, and the hardware for mapping it isn't too complicated to support on
an adapter card.
Dick
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Sunday, April 04, 1999 12:13 PM
Subject: Re: homemade computer for fun and experience...
>> Fire). One of those little switch boxes would serve just fine. The 8.0
MHz
>> Z80 wouldn't be sufficient to drive a VGA, so no need for anything fancy.
>
>Hmm... Don't VGA cards still have a hardware text mode? That's all you
>really need for the Z80 machine, and using it wouldn't be any worse than
>using an MDA or CGA card, once it's initialised.
>
>Of course that means you need to get a VGA card based on a documented
>chipset so you do know what to stick in all the registers. The on-board
>BIOS is going to be no use at all.
>
>I've seen a VGA card in a 4.77MHz 8088 machine, and it was usable for
>text and point-plotting type graphics. I think a Z80 could manage that as
>well. Of course you'd probably need some kind of paging hardware to map
>all the VGA's memory space into the Z80 memory map.
>
>The advantage of using a VGA card is that most people have a VGA monitor
>on their desk anyway...
>
>-tony
>
Received on Sun Apr 04 1999 - 13:39:01 BST