
Z80 computer wirewrapped on perfboard - tempodox
https://github.com/linker3000/Z80-Board
======
reaperducer
I love Z80 and 6809 machines. The first computer game I ever played was Zork
on a Z80. I keep trying to buy an old Z80 machine on fleaBay, but the prices
either start out of a reasonable range, or I get outbid.

It's great to see so many people these days rediscovering the chip and making
these modernized designs. Disk I/O was such an unreliable pain back then. It's
fantastic that most of these are designed for CF and SD storage now. Every
time I run across a project like this on the internet, I eat it up. And
thankfully, they are becoming more common.

If I had younger eyesight, and steadier hands, I'd be all over this project.
(Anyone know of a company that sells something like this I can hook up to a
dumb terminal? No FPGAs, or RPis, please.)

I met a woman just this past week who used to sell S-100 and Z80 machines at
BusinessLand in Silicon Valley back when everything was just starting to
percolate. We talked for hours about the experience and the people she met
what the valley was like back in those days. (Like getting to try out an Alto
in the 70's!)

The next time I run into her I'm going to encourage her to write all of that
down and post it somewhere.

[Edit to add:]

If you want an excellent CP/M experience on a modern Mac, there's Tom Harte's
emulator.† Unfortunately, I haven't been able to play the full Zork on it
because Zork requires multiple disks, and I don't think it has a mechanism to
switch virtual disks.

† [https://github.com/TomHarte/CP-M-for-OS-X](https://github.com/TomHarte/CP-
M-for-OS-X)

~~~
soneil
I've had a lot of fun with the rc2014 (rc2014.co.uk). You still gotta solder
it, but it's all through-hole 0.1", so nothing scary.

It's a very (very!) modular gig, so you can pick'n'mix what to match what
you're aiming for. from 32k & basic on rom, to banked ram, flashrom, cf, ide,
etc.

rpi & esp8266 optional.

~~~
reaperducer
Thanks for that link. It looks very promising!

Still needs a bit of soldering, but I may try to find a neighborhood kid with
better hands than I have to do it.

~~~
hartzell
I think it would be fun to build one of these, but I don't really have a use
for it.

I'm in the San Francisco Bay Area, let me know if you'd like to collaborate.

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linker3000
Hi folks, I see you found my 'parts bin' Z80 board!

Coincidentally, I'm reworking part of it on the desk in front of me right now.
I'm removing the address decoder (top left) for the I/O (LED) port and am
replacing it with a control line from the GAL (which is now a 22V10 instead of
a 20V8).

Apart from giving me something to build, the intention is to use the board as
a STEM show-and-tell item during school visits and local 'Jams' \- I am a
volunteer STEM ambassador in the UK and my company kindly gifts employees
several 'volunteering' days a year for local activities, so I help out with
career & STEM days as well as weekend special events (eg:
[https://twitter.com/linker3000/status/1020709404843421696](https://twitter.com/linker3000/status/1020709404843421696)).

Since I had the GALs to hand, using one is fine for me - but for those who
haven't got a programmer it would be a bit of an expense to tool up for it, so
I don't expect many to copy the design.

Someone asked in another thread about the single-sided wirewrapping technique;
it IS really quick to do, is easy to trace where you're going to/from, rework
is quick, PLUS as a STEM show-and-tell, everything is on one side so it can be
left on a desk and doesn't need to be constantly picked up/put down to see
everything; this reduces the risk of damaging the wiring and board.

Edit: The DIY retro build computer guys are really friendly and helpful, so do
drop by and see what's going on:

[https://groups.google.com/forum/#!forum/rc2014-z80](https://groups.google.com/forum/#!forum/rc2014-z80)

[https://www.retrobrewcomputers.org/forum/index.php](https://www.retrobrewcomputers.org/forum/index.php)

[https://www.retrobrewcomputers.org/doku.php](https://www.retrobrewcomputers.org/doku.php)

[http://6502.org/homebuilt](http://6502.org/homebuilt)

There's other places out there too, those are just the ones I've actively
used.

Thanks for the attention.

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Johnny555
Is that same-side wirewrapping really better?

The project site lists several advantages including faster re-works and it
being easier to see what you're connecting, but that doesn't seem to be the
case since all of the wires are crammed into little channels between the
chips.

On the underside of the board there's more room to spread the wires out,
making it easier to see the pins and to find the wire you need to re-work -
usually you can trace the wires visually, especially if you do some color
coding.

They don't seem to be too hard to find, Jameco and Mouser (among other places)
carry them, a 40 pin socket for a Z-80 costs $5

~~~
pjc50
Pin 1 remains at top left, as it will be in the diagrams on the datasheet,
rather than having to mentally flip everything. That's the possibility I can
think of.

~~~
Johnny555
When I started wirewrapping, I'd use a magic marker to place a dot at the pin
1 to make it easier to visualize on an upside down board.

For a while I did some wirewrapping for a company (defense contractor) and the
boards came drilled and with silkscreened component markings much like you'd
see on a PCB. It's not clear why they went through all of the trouble to
silkscreen and drill boards for wirewrapping and didn't just make PCB's.
Probably a combination of the cost to create PCB's coupled with a low
production run (they were building 5 custom products, so a pretty low volume)

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ArtWomb
This just demonstrates the Z80 love will never die ;)

Chips4Makers.io has just launched their own crowd funding campaign (seeking
$22K) for the Retro-μC. A fully open-source micro-controller that runs three
venerable retro CPU cores: the Zilog Z80, MOS 6502 and Motorola M68K. Yes, you
read that correctly. It's like a TRS-80, Commodore-64 and Amiga on a single
chip!

[https://www.crowdsupply.com/chips4makers/retro-
uc](https://www.crowdsupply.com/chips4makers/retro-uc)

~~~
linker3000
Yeah, but it's already been done:

[http://searle.hostei.com/grant/Multicomp/index.html](http://searle.hostei.com/grant/Multicomp/index.html)

~~~
thinkmassive
Right! It seems like anyone who wants a retrocomputer on an FPGA would want to
program it themselves. Considering you can get an EP2C5T144 dev kit for $20,
and a USB-blaster for $10, I’m not sure I see any market for a $42 pre-
programmed FPGA that may not be supported after it ships.

------
TomVDB
My first ASIC was validated like that. A much larger wire wrapped board with a
bunch of FPGAs.

It only worked if you gently pushed with your hands into the wires, but it was
sufficient to discover a bunch of bugs (that should have been found in
simulation, but we were total cowboys back then.)

~~~
analog31
Your hands may have created some subtle RC time constants that killed a race
condition.

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passthejoe
The kicker is that it runs CP/M -- the demo shows WordStar

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zerealshadowban
My first assembly language was Z80, not really hard but not a lot of fun. Then
along came the Motorola 68000 and _that_ instruction set was bliss.

~~~
stevekemp
I was lucky, in the sense that I jumped from Z80 to 386/486/etc. Because Zilog
was basically founded by ex-Intel staff the instruction-sets weren't too
dissimilar.

I could never get my head round 6502-instructions (as a teenager). These days
I guess my knowledge is largely obsolete as I stopped writing Intel assembly
language around the time SSE came out. Still there are times when I decompile
& patch binaries for fun, so it wasn't entirely wasted.

------
garganzol
Please note that one of the screenshots shows:

    
    
      Z80 CP/M BIOS 1.0 by G. Searle 2007-13
    
      CP/M 2.2 Copyright 1979 (c) by Digital Research
    

A curious thing in all that is that Gary Kildall, the founder of Digital
Research and the creator of CP/M, invented the concept of BIOS back then in
the late 70s. We still use it today!

Please note how closely that CP/M boot text resembles newer variants we still
meet in modern PCs.

------
iforgotpassword
How much more work would it be to build something similar with a 486? (Just as
an example since I have such a CPU sitting on my desk). It's quite some more
pins for sure, but how many of those are essential? And I don't mean to build
something IBM PC compatible, just something that barely boots into some kind
of shell and can run a basic interpreter or similar. Has this been done?

~~~
CamTin
It would be very difficult to wirewrap a board that could support a 486,
starting with the fact that I'm not sure wire-wrap sockets exist for it, so
you'd either need a breakout or to get one custom-machined.

Once you have that, you'd want to think about clocking the chip way under its
typical speed and seeing if it still gives useful results, because birds' nest
wirewrap is not going to be especially useful at 16mhz.

You're right that most of the 168 pins in a typical 486 socket are not
necessary or are redundant. At minimum you would need power, some address pins
(probably not all of them, if you're only looking to run the most minimal
program, call it 16 for a two-byte 64k address space), some data pins (again,
you can probably get by with 8 if you're willing to use the 8-bit instructions
only). There are a few misc pins that I don't know the exact use of, but
you'll probably need 4-5 to do things like understand when the bus is in use,
set up 8 bit bus mode etc.

Then you can think about what kind of i/o you want. For a minimal project, you
can probably get by with driving LEDs straight from from address pins (i.e.
read from a certain address in a tight loop to light it).

From here you can blow some ROMs with simple programs and convince yourself it
works, but at this point you're really just treating a 486 like a 70s era
micro (8080, 6502, CDP1802, etc) in a "trainer" like the KIM-1
([http://www.6502.org/trainers/buildkim/kim.htm](http://www.6502.org/trainers/buildkim/kim.htm)).

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abainbridge
That's beautifully neat bit of wirewrapping. And the layout is very
aesthetically pleasing. It feels like such craftsmanship should yield a
computer faster than one you can buy off-the-shelf.

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Lunatic666
The StarTrek game was the first game I ever played. I asked my father to teach
me decimals to fire the photon torpedos properly. Seeing this again brings
back some really early memories.

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peter_d_sherman
Utterly brilliant!

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amelius
Posted a bit too late :)

