homebrewed 32-bit cpu?

[David Griffith]

On Mon, 2 Apr 2007, Grant Stockly wrote:

> I've thought about it.  I actually entered half the schematics for the
> Magic-1 into my schematic program.  I was going to produce some PCBs for it
> for a kit.  I ended up giving up because I needed to spend time on the
> Altair effort.

Nifty!  I entered the ALU and part of the control board entered into
gschem with the same intent.  Perhaps we could collaborate on that later
on.  I made some alterations to allow use of a bog-standard VME chassis.

> A goal of mine would probably be a TTL 8080 or completely a
> transistorized  (as in pbysical little black dots : )  ) 8080.  The idea
> behind that is it could be an extension to the Altair kit...

On one of the pages linked from the homebrewcpu.org page is a project that
uses surface-mount transistors on what amount to tiny flipchips.  If
you're insane enough to try a discrete 8080, go with that approach.

> I have thought about a 32 bit CPU built like the Magic 1, and in fact drew
> up the schematic for the ALU.  I thought it would be fun to build a
> computer using parts available in 1975 that was capable of decoding an
> MP3.  For speed designed a schematic for a 32x32 combinatorial
> multiplier.  :)  I think I estimated it would draw 5A (just the
> multiplier)...  ; )

At that rate, the complete machine might demand 20 amps or more.

> And no, it would not be the same if it were in an FPGA.  : )

Of course!

> The 8080/transistor computer would have an LED for every transistor.  Can
> you imagine how cool it would be to single step that thing?  : )

At least I'd like to have LED displays for each bus, each flag, and each
register.


-- 
David Griffith
dgriffi at cs.csubak.edu

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