Sinclair ZX80 / ZX81 / Z88 Forums

Hi Kelly,
of course the Inkey$ and INPUT routines can only detect valid keys. But, as I wrote, scanning the keyboard directly by using IN/OUT, a m/c program can detect multiple keys being pressed. E. g. there are games, which accept all keys connected to a keyboard column as one key and another column as second key.
And I also once wrote a BASIC(!) program, which could detect multiple keys (AFAIK by comparing system variable LAST_K).
Try the attached game "HARRISBURG" (to control an ATOMKRAFTWERK : pressing D and also K(for '+') or J(for '-'"), you will open or close the steam valve (DAMPFVENTIL, right upper corner). Or use S and K(for '+') to pull a "STEUERSTAB" out the reactor core or S and J(for '-'") to push it back into the core (upper left corner)..

This game cannot be played by joystick, but by using the keyboard ...

Siggi

This is one more example, where multiple keys may be pressed at the same time: while holding the fire button down (e. g. SPACE key), it is possible to move the craft up(A)/down(Q)/right/left:

http://www.zx81stuff.org.uk/zx81/tape/3DDefender

siggi wrote: ↑Sun Mar 08, 2020 12:08 pm This is one more example, where multiple keys may be pressed at the same time: while holding the fire button down (e. g. SPACE key), it is possible to move the craft up(A)/down(Q)/right/left:

http://www.zx81stuff.org.uk/zx81/tape/3DDefender

But Siggi, the interface works like this, I don't understand.

The setup program takes into account all valid combinations between keys, such that the interface can respond to multiple key presses.

Indeed, it works like on a real keyboard.
It seems, that I played a game, where also the keyboard does not support multiple keys.
Sorry for the confusion I made

Siggi

Does anyone have a spare they'd be willing to part with or know if they're still being made?

system11 wrote: ↑Wed Apr 19, 2023 1:03 pm Does anyone have a spare they'd be willing to part with or know if they're still being made?

OP @kmurta is a regular poster in this forum. You can send him a message.

I don't have a physical zx81, Can you make a rom dump or image of the interface for emulation?

I know that there are still people interested in obtaining a JOY81, but unfortunately at the moment I am unable to start producing a new batch.

I still have some PCBs left but unfortunately the cost to send them outside of Brazil is excessive (more than 30GBP), so I will make the files available here for anyone who wants to produce their own interface at a perhaps more affordable cost.

Feel free to use it as you see fit.

I just ordered 20 for europe.
If no one is offering for UK I'm willing to send there too. No sending to rest of the world.
Prices when I received them.

Remembering that you must provide the piggyback connector, although I think this other solution is better: https://www.zx81keyboardadventure.com/2 ... iGfnhStNoE