Building a Z-80 (64bit!!!)

From: Allison J Parent <allisonp_at_world.std.com>
Date: Wed Oct 21 19:22:44 1998

< Okay, here's another hair-brained project that I am working on.....
<
< I am trying to basically build a 64Bit Z-80 on a board. What I am
< looking for is: Anyone know of any chips that are EXTREMELY simple
< micro-controllers but, work at EXTREMELY high clock rates??? I wanna p
< a few on a board with some memory and made a 64-bit Z-80. I'd like th
< processor to operate at 300Mcyc (or faster) clock speeds so, I figure I
< need micro-controllers that operate at about 900 Mcyc to do the work.
<
< Any ideas????

Wait till April first for this.

I don't think you were listening when we were discussing propagation
delays. To deal with 300-900Mhz clock your talking 4-6layer etch and
some really fast logic. The .33nS memory will be tough to buy. Be
prepared to dump a few DecaKilobucks into the attempt after all you'll
need a really fast logic analyser and O'scope to see what you missed.

If you want a 32 bit z80 get a z380, it runs native z80 code, until you
switch modes then compatability works but it has a lot of gotchas.

If your doing a z80 stretch, you better think about how to access memory
or really alter the z80 fetch timing. Basic Z80 timing for say 20ns
memory would limit you to some 40-50Mhz... it would be a 5-10 MIPS machine
though. If you superpipline it and get it down to 1-2 clocks per cycle
you can double that. In any case there is no way to logically stretch a
z80 without running the risk of making it software incompatable at some
point. I've seriously looked at it, still have the 2901s I was thinking
of using. I have z80/10mhz parts however and the 2901s would barely do
that.

FYI: z80S180s can be had into the 30+ mhz range.


Allison
Received on Wed Oct 21 1998 - 19:22:44 BST