Sinclair ZX80 / ZX81 / Z88 Forums

Hi there.

I was wondering if it's possible to make a joystick-interface for ZX81.
This comp seems to be more games-oriented than demos-oriented.

And the keyboard can not stand such intensive using.

We have interfaces on Spectrum, connected to zx-bus. They actually read simply keyboard's ports.
When I press buttons on my joypad, the comp press keys simply: 1,2,3,4,5. Or others in other ports or interfaces.

Many games have "redefine keys" option. Then I even don't think what kind of joystick-interface I have but simply define keys using joystick.

I think it should be possible on ZX81.

What do You think?

PS: And maybe there IS already such an interface.....? But I can't see it mentioned in games 'though.

Yes, the Spectrum kempston and Protek (Cursor key) joystick interfaces should "just work" on the ZX81. The only issue with the Kempston is that you can't read it in BASIC due to the ZX81 having no IN keyword. Not an issue with M/C programs though.

Mike

Hi, well recently I receive a copy of the SYNC Magazince from January/February 1994, on page 3 there are an anounce from Zebra Systems, INC offering a lot of products and including one Joystick Adaptor, the interesting thing is that the publicity says that comes with a FREE PATCHKIT #1 shows patches for Timex Flight Simulator and other popular games... so I think that this adaptor do not emulate the keystrokes, is posible to emulate the keystrokes from the expansion port ? I mean without any software part ? or we ever need to path / adapt the softwares ? anyone has more info about the Zebra Kits ? I look on the zx81stuff.org but there are no matching results... I find on the WEB and I found a company that actually... well tha discovery will go to the MISC forum
Gus

Hi Gus. I wonder if the people at the german zx81 group have reverse engineered any of those interfaces. See my reply to your thread in the misc forum.

@yerzmyey: If you would like to have a glimpse of what the ZX81 users had available back in the day, please read some of the Sync magazines. Sync was an american magazine for Sinclair and Timex owners, and the content was amazing. You can read some of them by going here:

ftp://ftp.worldofspectrum.org/pub/sincl ... ines/Sync/

I will be uploading more Sync magazines soon, very soon.

gus wrote:is posible to emulate the keystrokes from the expansion port ? I mean without any software part ?

Yes. There were several replacement keyboards for the ZX81 that plugged into the expansion port. The simplest joystick interface to make would be similar to the Spectrums IF2 - using keys 1,2,3,4,5 or 6,7,8,9,0 for the joystick. However, a cursor key (5,6,7,8 and 0) isn't much more effort and a lot of games would work without modification.

Mike

Mike:

>Yes, the Spectrum kempston and Protek (Cursor key) joystick interfaces should "just work" on the ZX81. The only issue with the Kempston is that you can't read it in BASIC due to the ZX81 having no IN keyword. Not an issue with M/C programs though.
-- ---------------
Well, on Spectrum the interface simply backups/doubles proper keys on keyboard.
So I could use it in BASIC games on ZX81. List them, find keyboard procedure and change keys from original to 1,2,3,4,5 (taking one of my interfaces as an example).

Then it could work, if You're right the Speccy boxes should work also with Zeddy.


However GUS wrote:
>is posible to emulate the keystrokes from the expansion port ?
-------------------
And this is key-question, I'm afraid. I assumed it is possible.
I can simply type digits in BASIC, with my joystick-interfaces on Spectrum.


If emulating the keystrokes from the expansion port on ZX81 is not possible - and if requires machine code - then the idea is kinda dead because even if there is joystick interface for ZX81 (or if it's possible to use Spectrum's ones) - there is no software for it. And also it's impossible for avarage game-player like me to rewrite the games.

The idea was based on assumption that everybody can change controll-letters in BASIC listing.


Bruno: thanx for da link, I will check it out gladly.

Mike wrote:

gus wrote:is posible to emulate the keystrokes from the expansion port ? I mean without any software part ?

Yes. There were several replacement keyboards for the ZX81 that plugged into the expansion port. The simplest joystick interface to make would be similar to the Spectrums IF2 - using keys 1,2,3,4,5 or 6,7,8,9,0 for the joystick. However, a cursor key (5,6,7,8 and 0) isn't much more effort and a lot of games would work without modification.
Mike

If so - then everybody (I think) could change BASIC games to use them with it. More/less.

But btw - the interface should be similar or can it be the *same* interface, taken from Spectrum?

Thx for the infos.

yerzmyey wrote:Then it could work, if You're right the Speccy boxes should work also with Zeddy.

I know the Kempston interface works on the ZX81 - I've tried it. However, as I said the kempston is the hardest to read on the '81 due it not simulating keypresses but using port 31. An AGF/Protek (Cursor key) interface should work, as long as it uses the smaller edge connector of the '81 instead of the larger spectrum version - a lot of earlier spectrum interfaces did if they didn't require the extra lines the spectrum made available.

However GUS wrote:
>is posible to emulate the keystrokes from the expansion port ?
-------------------
And this is key-question, I'm afraid. I assumed it is possible.
I can simply type digits in BASIC, with my joystick-interfaces on Spectrum.

Try that with a kempston interface

Mike

Mike wrote:

gus wrote:is posible to emulate the keystrokes from the expansion port ? I mean without any software part ?

Yes. There were several replacement keyboards for the ZX81 that plugged into the expansion port. The simplest joystick interface to make would be similar to the Spectrums IF2 - using keys 1,2,3,4,5 or 6,7,8,9,0 for the joystick. However, a cursor key (5,6,7,8 and 0) isn't much more effort and a lot of games would work without modification.

Mike

Well so all we must to do is a new "FREE PATCHKIT #1" !!!
But somebody do already build a simple joystick external interface ? I do prefear it on the external form in order to mantain the aspect of the original machines, and of course so I can use it with the Timex Sinclair 1000 or the zx81 or the Timex Sinclair 1500
If I can "build" the interface I will do the new patchkit by sure

Gus

Hi Gus,
There's an keyboard exemple here

http://zx81.ordi5.free.fr/brico/clavier/

You can add currsors keys to make a Joystick !

English:
http://translate.google.com/translate? ... uage_tools