[geeks] WANTED: chip level design software for UNIX/Linux

[Charles Shannon Hendrix]

I've been playing with more low level toys lately, so I have some
questions about learning small computers.  I know that Bill mentioned
Z80 stuff in the past and some of the rest of you, so I figure you'll
have some ideas at least.

First thing: I'm going back and relearning basic computer circuits. I
can't really afford to set up the real hardware since I've gradually
thinned out my parts over the last 15 years.

Instead, I'm thinking of learning it under simulation.

I've looked at spice, but it seems to only do base level discrete
components, not chip level parts like 74LS* series, etc.

In college we used Cadence, but that was mega expensive back then, and I
imagine still would be.

Anything out there that is free, and good enough for learning discrete
logic and computer circuits?

#1a

Almost forgot... I have a lot of Forest Mims books on circuitry.  One
set I seem to have lost was where he gave the basics of a 4-bit computer
system.  I recall it was his usual clear style.

Does anyone know of a reference like that, except covering 8 and/or 16
bit circuits? I know you can learn and expand on the 4-bit systems, but
it might be easier to start with them.

The most complex thing I ever made was a parallel adder out of 74 series
chips, but in spite of that underachievement, one of these days I want
to make my own CPU and system.  Some day.

#2:

I'm looking for recommendations on trainer systems.  Primary interests
are 8-bit micros, and maybe 32-bit MIPS.

So far what I've found is pretty expensive, at least for me right now.

Might be another area where I just decide to simulate it.  The only
thing is the simulators generally seem to emulate fixed hardware, not
let you expand them, etc.



-- 
shannon           | The grieving lords take ship.  With these our very souls 
                  | pass overseas. 
				  |         -- Exile