Help me make a home-brew Zilog Z80 CPU

[neazoi]

homebrew cpu

has anyone ever built a zilog Z80 out of simple TTL chips?

like this one http://www.homebrewcpu.com/

 

[randyest]

homebrew cpu

A long time ago in school. It was a huge pain to wrap all the wires. I hated doing it.

 

[eltonjohn]

Re: homebrew cpu

HI ..
This is how minicomputer used to be built in the 70s that's why you have all those TTL chips .With all kind of data moving possibilities .I recall the HP1000 and Hp3000 Cpus they were big boards full of just ttl chips and eproms.
I can say that the guy of that homebrew computer has a lot of time on his hands!!!
why stop there at the TTL chips level .Why not make it out tubes ! or even mechanical like Babbages machine.

 

[neazoi]

Re: homebrew cpu

I have seen some "crazy" guys making their own processors but I would like to find any plans for building a Z80 processor.

I know about wiring, this is just for interest I do not thing I will start such a project...

are there are any plans or internet sources?

 

[123jack]

Re: homebrew cpu

Just my feeling - do a 6502
Much more elegant design :!:

In fact I've often wondered how small and how fast you could make a 6502
these days... physically (not just emulation)

In my minicomputer days (80's) they didnt use micros like that. It was still chip slice logic (shifters across source/destination buses etc)

Interesting idea though.

jack

 

[neazoi]

Re: homebrew cpu

I am building a sinclair zx80 which uses a z80 processor just for fun. so I was wondering how difficult would be to expand the processor functionality into descrete logic.
As a homebrewn computer, I like better the zx80 from the zx81 and later models in the sense that later models use harder to find fpgas, fewer chips though.

 

[123jack]

Re: homebrew cpu

I was an Acorn Atom man myself - although I did have a ZX80.
The problem was - by the time the ZX80 had arrived I'd gone out and bought the Atom and assembled it.

And then the BBC micro came out and it was all change again...

The good thing about all these early computers was the emphasis on PORTS.
That tended to force people to learn.

Perhaps a project to build a micro from scratch is just what's needed.

Inmos transputer anyone ?

jack

 

[neazoi]

Re: homebrew cpu

Thank you all for your replies.

Are there any 1-bit ALU schematics out there?

I was thinking of making a very basic computer/alu that will be able to do the basic Integer arithmetic operations and Bitwise logic operations. For the starting point I was thinking of using the eniac architecture, where there the actual program was set up using witches.

For example I could set one byte using switches and then another one and then perform addition to them through the ALU. so simple work actually...

 

[123jack]

Re: homebrew cpu

neazoi

Yes thats how mini computers used to work but there is no such thing as "integer arithmetic" at this level.

All you have is shifters you can clock left and right and registers to catch the output.

You might be able to find something that does more - but then why not just by a
pentium and use that.

You build your ALU from shuffling bits around. Its your project of course and you can start where you like but it does seem kind of self defeating to start too high
up the chain to me.


jack