Sinclair ZX80 / ZX81 / Z88 Forums

A few month ago I developed a pcb to realize a keyboard for a ZX81 which can be easily used as a replacement keyboard as well instead of a simple membrane.
The reason for development was mainly for a ZX81 replica from the german user holmatic which is called ZX81NU with pure discrete logic instead of a ULA.
Many people like a more comfortable keyboard feeling while typing and so the idea was born to build up a keyboard (initiated from german Paul).

So this keyboard can replace any ZX81 membrane while simply putting it on top of the old membrane - so it is fully reversable to keep the original state of a ZX81.


the board itself - smaller in thickness, just 0.8mm instead of the standard 1.6mm, so half in height

assembled here with the ALPS SKQGAFE010 tactile switches with low profile (1.5mm) and MOLEX jumper cables to easily connect the replacement keyboard to the MOLEX connectors on the ZX81, the jumper cables (type 25001) are flat cables with a half-solid core (drilled and soldered wires on the full length) which give both, flexibility and rigidity

the jumper cables are passing the hole in the case quite comfortable and the old membrane can be left there or removed - up to you

the height of the complete replacement keyboard is about 2.5 mm or 1/10 inches and this doesn't harm optically when placed on top of the membrane or case


the rigid ends of the cable jumper can be feeded easily into the board (with some care to hold it straight while pushing it into the plug)
the contacts are not wided too much so when removed the thinner membranes will hold as well again

The cables are flexible enough to bend them in a small curve to fit under the board:

Here is a variant using pin headers (to the ZX81NU):


and there is a variant with ZX80 top cover instead of ZX81 layout available as well, just in case:

That looks excellent - the one thing I would warn about is the graphics for the overlay, as some of the ones on the web have minor errors....

RWAP wrote:That looks excellent - the one thing I would warn about is the graphics for the overlay, as some of the ones on the web have minor errors....

I did check this carefully with my own original ZX81 and they have not been copied from the web but created manually new by hand.
By the way - the membrane contains also the ZXpand tokens DELETE, CONFIG and CAT.




The solution ZX8-KDLX is available as board only, assembly kit and complete "manufactured" keyboard - so easily to use for everyone on sellmyretro:

http://www.sellmyretro.com/user/profile/PokeMon


And ZX Spectrum (16/48k) keyboards are available soon as well as they are used for the german Harlequin users ...

Brilliant! Superb work as always, Karl

It is still fit sales?

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Mark