Sinclair ZX80 / ZX81 / Z88 Forums

All,
I want to do a project of making up a ZX81 fully loaded in a different case and proper keyboard.
I used to do this years ago for making Z80 controllers. But that was a life time or two ago lol.
So any suggestions? What keyboard is available that can be 'hacked' made to work etc?
I used to rip the supply out and the modulator then solder ram pack components direct onto the edge connector and put the lot in a metal case. At the time ZX81's were 'ten a penny' lol.
alan

Hello Alan. Welcome to our Zeddy forum

Keyboards - It very much depends on how much money you want to spend, what parts you have and what result you want.
You could look / search / keep an eye out for a replacement keyboard that was available back in the 1980's (e.g. Memotech keyboards come up every now and again on eBay).

If you can find an old broken computer that has a keyboard with real keyswitches, you could cut the tracks, then rewire it to the matrix used by the ZX81.

Or you could buy switches and make your own. Real keyboard switches and the caps are still made, but are a bit pricy. Or you can use the much cheaper PCB click switches, but would have to come up with a way of labelling the keys.

Mark

On the Acorn forum StarDot it's often joked about (but I think people are sometimes quite serious ) that Acorn Electron computers are only good for keyswitch donations..! On *. it's a joke but I think if I suggested it here it may be regarded as heresy - what do you think Mark

I must admit that I do keep an eye out for broken 1980's computers where I could reuse the keyboard or the key switches. Not that I have come across many so far.

I have bought some inexpensive Acorn Electrons where the listing was not clear if they worked, but they all more or less work (minor faults like aged solder connections on the power jack socket). One does have a faulty enter/return key that I haven't looked into yet. This one may be used as spares for a Acorn BBC Master that has more faulty key switches than working ones, but the rest of the machine works okay.

But in general, I prefer it if only unrepairable computers are used as keyboard donors.

Mark

As far as ZX81s are concerned, I have some where the original membrane is still okay, some with a replacement membrane (from RWAP / Sell My Retro) and I have some 1980's replacement keyboards. One is a Memotech, the beauty of this type, is it just plugs in the expansion edge-connector port, so is great for testing ZX81s when their membrane is faulty.

There were over five makes of replacement keyboards for ZX81's in the 1980's.

Mark

1024MAK wrote:There were over five makes of replacement keyboards for ZX81's in the 1980's.

Mark

Where are they when you need them! lol
Alan

I have a ZX81 that I built into a Dell PC keyboard, I cut out the numeric keypad and mounted the 81 board there + internal 32K ram. Main part of the keyboard has been re-wired in ZX81 format, works well

Cheers,

Phill.

Prime wrote:I have a ZX81 that I built into a Dell PC keyboard, I cut out the numeric keypad and mounted the 81 board there + internal 32K ram. Main part of the keyboard has been re-wired in ZX81 format, works well

Cheers,

Phill.

Pictures?

1024MAK wrote:I have some 1980's replacement keyboards. One is a Memotech...

Have you tried that Memotech with the ZX80core? Does it work for you?

I have one and it doesn't work, but I suspect it could be the keyboard or interface itself that's faulty, rather than an incompatibility.

My ZX80core is still under construction...

However, if you build the ZX80core as per the instructions, then the Memotech keyboard will not work.
The ZX80core and the Memotech keyboard both have normal chips with totem-pole push–pull output stages - so you get a bus conflict. In order for the Memotech keyboard to work, a chip needs removing, however it's not that simple as this chip has another function...

Once I have finished working on my other projects (Jupiter Ace kit), this is an area I plan to look at.

Mark