ZX81 toZX80 conversion.

[siggi]

I have just the tool for the job!!

No, that tool makes longer slots on the outside and shorter on the inside.
I think, that is a better tool (also for other problems) ...

[Moggy]

I have just the tool for the job!!

No, that tool makes longer slots on the outside and shorter on the inside.
I think, that is a better tool (also for other problems) ...

[Spinnetti]

Those "clicky" keyboards are fantastic quality. I have several!

[Moggy]

Those "clicky" keyboards are fantastic quality. I have several!

They are a lot easier to install now that Karl includes two little "finger" boards to go into the motherboard sockets rather than just the ribbons, indeed most excellent.

[Moggy]

Having done this conversion and it working well I have decided to ditch the tape covered case and, seeing Charlie's own white cased version, take Lardo's advice re painting, it so a tin of primer and acrylic gloss white are on order.

Whilst I wanted a touch of originality I decided a bit more usability was in order hence the fitting of a switching reg, one of Karl's video boards and a "clicky" keyboard.
One aspect I wasn't too happy with was having to revert back to tape loading so I programmed another EPROM with the ZX80 ROM image plus the ZXpand drivers and so now have quick load and save, rendering tape use defunct.

One thing I mentioned in another post was that it didn't play nicely with "flicker free" displays. After burning the latest EPROM and using it with the spand I now find some flicker free stuff working, example omissions being the Metropolis demo and flicker free 1k FIDE chess.

Why this should be I cannot say but possibly a timing discrepancy of some kind.

I've enjoyed this little sojourn into zeddy modding and taking everything into consideration moneywise it's cost me a tad over £50 ,some bits were already on the ZX81 board, and for anyone who has a spare ZX81, a suitable chip to program and the other bits and bobs well worth the effort, the alternative being, for anyone wanting the ZX80 "experience" , is to buy one of those "Untested-no returns-broken case-no leads or power pack affairs that are listed usually just shy of a grand on a certain auction site.

I know which I prefer and for anyone wanting to have a go themselves, have fun!

[redgatemodels]

Would a ZX81 pcb fit in a ZX80 case? there are a couple of projects on Thingiverse for the ZX80 case ...

[Moggy]

No they are two totally different beasts.

Top picture ZX81 bottom picture ZX80.

[Paul]

Well, if you take away the cooling pad and desolder the modulator you might be able to put the ZX81 PCB upside down into the top right corner the connections could be in the correct order for power and tape.
If you resolder the modulator to the bottom side of the PCB it might nearly line up with the TV output
Everything would be upside down but it could work.

The keyboard connectors would be on the bottom side as well.
The clicky keyboard from Karl might fit to the bottom part of the ZX80.
Why not try this funny Frankenstein ZX80

[Moggy]

Ah but the ZX81 ports read as EAR-MIC-POWER top to bottom whereas the ZX80's would read as MIC-EAR-POWER if turned sideways!

[Paul]

There is always a little uncertainty which port needs to be connected to which cassette recorder connector