[Coco] Proto CoCo
zmerch-coco at 30below.com
Mon Aug 28 14:34:14 EDT 2006
Rumor has it that Gene Heskett may have mentioned these words:
>I can do the routing on my cnc micromill. That shouldn't be more than 30
>lines of gcode to hand carve a working approximation of that edge profile.
That's one of the main things that's been stopping me from a pet project I
started about 5 years ago... The other thing was drilling *all* those holes
for a fair amount of TTL to do the buffering/latching/address decoding for.
>But I'm also partial to having the address decodeing and buffered bus stuff
>all present and accounted for.
Which is what I had started implementing...
> Ditto OC buffers for all the IRQ related
>stuff so we don't see the IRQ's blinking the video slightly since there's
>way too many pullups using way too low R's in the average lashup.
This is what I'm less knowledgeable about.
What I'd originally wanted to design/build was a buffered bus "companion" -
with a ROM socket, integrated latched I/O, *full* address decoding for
several addresses, a small breadboard, and pin headers for wire-wrap access
to the bus signals... and if I got way overproductive, maybe some built-in
A/D\D/A to boot. Basically the "ultimate" hacker/experimenter board for the
However, the board space for all the 6-bit/8-bit buffers & latches started
taking up quite a bit of board space.
Now that the 16-bit buffer chips are out (and in surface-mount) (and I have
access to some on some spare boards) the board would be much easier (read:
less drilling) to build with a lot less board real estate consumed just for
the primary support chips.
I also wanted to put the address decoding I felt was necessary into a
PAL/GAL instead of diddling with individual AND/OR/NOR gates, but I'm
obviously not smart enough to understand those critters; as there's no such
thing as a "PALs/GALs for Dummies" book yet. I guess there's a reason for
I think I still have all the files WRT my project (and I even think I have
the original (not complete) board artwork (done in AutoCad - it's all I
know ;-) *somewhere*...
If I wasn't going 7:30 am -> 3:00 am maybe I'd have time to restart the
project again... ;-)
BTW, is there any good all-around circuit software for Linux - *but* not a
standard Linux distro? PCB compiled fine on my Linux From Scratch machine,
but gEDA barfed horribly last time I tried to build it - in such a way that
it confused me no end (no surprise there) and I gave up on it. I'd consider
any halfway decent package, good libraries a plus but certainly not
necessary (but bonus points to software that's especially easy to *make*
Roger "Merch" Merchberger
Roger "Merch" Merchberger | Anarchy doesn't scale well. -- Me
zmerch at 30below.com. |
SysAdmin, Iceberg Computers
More information about the Coco