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C4P joystick project

Posted: Sun Mar 17, 2019 1:05 pm
by mjmalecha
Some assistance please. I am attempting to get a joystick working with my C4P. But no luck so far. I found an article that advised how to re wire an Atari joystick. I also have the A15 board schematic. It appears that the computer uses pins 1-6 in this order; 1 - GND, 2 - down, 3- left, 4-right, 5- up, 6- button. If that is not correct please advise. In the manual it provides poke/peek commands - but when I peek 57088 and do the ADD (not really understanding that part, but regardless. I cannot get a successful PEEK to verify joystick position. When I move the joystick, it puts various letters on the screen like its acting as a keyboard. (if inserted in joystick A port it locks up the computer and I need to reboot. So in effect (unless I right a basic program) I cannot even do the PEEK, because moving the joystick puts characters on the screen. I did write a program, but the value in PEEK 57088 never changes from 1. (joystick A) or 0 (joystick B) regardless of joystick position. If anyone has experience with this, would sincerely appreciate some help. There is not much of anything written online about the joysticks. Thank you, Mike

Re: C4P joystick project

Posted: Sun Mar 17, 2019 5:11 pm
by waltermixxx
any chance you can provide a link to the article you are working from?
just so anyone reading might be on the same page? as well as a link to the
schematic for the A15 :) It might help anyone willing to take the time,
and have a C4P :)

Cheers.

Re: C4P joystick project

Posted: Sun Mar 17, 2019 10:04 pm
by mjmalecha
Absolutely. I just have a hard copy, but I will scan it and attach. The schematic is from Dave's OSI page, in the list of boards the A15 is one of them, click on it and it's the schematic. Mike

Re: C4P joystick project

Posted: Sun Mar 17, 2019 10:11 pm
by mjmalecha
Here is the article describing how to modify the Atari joystick. Note the suggested jumper on the A15 board is likely because in an original Atari joystick, pin 5 is not wired, but if you wire a new cable/connector on the joystick - you should not have to modify inside the computer but just move 8 to 5. However, I do not have it working yet, so.......
joystick conversion
joystick conversion
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Re: C4P joystick project

Posted: Mon Mar 18, 2019 12:29 pm
by waltermixxx
i mentioned this thread to Steve Gray who says he has the A15 board,
and is using it with an Atari Joystick, hopefully he will respond soon,
with his experience getting it to work :)

Re: C4P joystick project

Posted: Tue Mar 19, 2019 1:03 am
by Steve Gray
More like "used it with"... It's only been 35 years ;-)
I basically compared the OSI pinout to the Atari pinout and rewired it to match. It's a bit of a mess.
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DSC08517-P50.jpg
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Re: C4P joystick project

Posted: Tue Mar 19, 2019 1:23 am
by mjmalecha
Thanks Steve, I appreciate you sharing this. Question - it appears all of your rewiring is involving the two post closest to the J11 (keyboard connector) - on your 2nd photo they would be the bottom two, in all the C4P manuals I have seen, the joystick ports are the top two - the two that you did not appear to rewire. Is this something I should investigate? is it possible the joysticks are the lower two ports? not J5 & J6? thanks. Mike

Re: C4P joystick project

Posted: Tue Mar 19, 2019 1:54 am
by Steve Gray
You got me there... I don't know why i picked those two... perhaps to keep the ability to use OSI joysticks should the need arise.

I can look to see if i have any notes, but it would probably be easy enough to just look at the a15 schematics and the c4p manual to figure it out again.

Re: C4P joystick project

Posted: Tue Mar 19, 2019 1:57 am
by mjmalecha
Thanks, that what I have done, but as you can see from my initial post, its not working, so I have to roll up my sleeves and get in and get dirty! I appreciate your comments. Thanks!

Re: C4P joystick project

Posted: Fri Mar 29, 2019 4:42 pm
by mjmalecha
Can someone advise if it is normal to see characters produced on the screen when moving the joystick? I assume this is not correct and indicates a wiring/routing error, but confirmation would be helpful. Thanks! Mike