Sinclair ZX80 / ZX81 / Z88 Forums

Well their have been solutions provided by the german ZX team in the past.
Because the ULA outputs are open collector with a pull up and pushed down by a keypress and corresponding address line you can do the same over the edge connector if you listen to the IN address ($FE) and can either use the same matrix or any circuit simulation a keypress. With that you can use internal and external keyboard at the same time or use several external keyboards and maybe develop a kind of game using keyboards.

There has been an official product from Memotech:
http://www.zx81stuff.org.uk/zx81/genera ... board.html

And here is an article of the german ZX team for adapting an AT keyboard to a ZX81 (german language only, beginning from page 11)
http://forum.tlienhard.com/magazin/1996/magazin_396.pdf

Also from Wilf:

http://www.user.dccnet.com/wrigter/inde ... XKBDv3.htm

C

Thanks for the info

So the prototype board arrived and test is in progress.
Looks good so far.

Clock working
CPU working
ROM working
RAM working

video and keyboard will be tested tomorrow.

Here two first pictures ...

component side
solder side
For more pictures you may look in this thread of the german board, from page 7 on (if posts ordered ascending time).

http://forum.tlienhard.com/phpBB3/viewt ... &start=150

I hope the testing continues to goes well
I do like good news

Mark

WHOAH!!!

Cool!

Fingers crossed.

Very good - another ZX80 for my collection

Here one more pic how it looks like components.
Today more tests passed.
Video unit is working 100%, got a nice picture.
Keyboard is working 100%, could type in very good.

Tomorrow some more final tests with LOAD/SAVE, NMIX Board (NMI generator plus video enhancement), different RAM / ROM / EEPROM configurations, using expander slot.

VERY nice! All that's needed now is some 'reproduction' cases!!!