PC to Apple II joystick adapter?

[carlsson]

The other year, I tried to build a PC to Apple II joystick adapter according to this schematic:
http://apple2.org.za/gswv/a2zine/faqs/R029PCA2XRF.GIF

As far as I can tell, the [4] and [5] on the PC joystick side really are GND lines misplaced on the diagram.

When I plugged this adapter into my Basis 108, an Apple II+ clone, I get good readings on the pots: up, down, left, right after some calibration, but the buttons don't work! I have tried five different PC joysticks, of which one reads out the fire buttons in cyclic patterns: on-off about once a second if the button is held down. On the other joysticks, they don't register at all. I tried to disable any autofire function with no difference. At least one of those five joysticks completely lacks autofire functionality.

So I rebuilt the above adapter to the slightly more complex variant to work with autofire joysticks:
http://apple2.org.za/gswv/a2zine/faqs/R030PCA2RF.GIF

However after this mod, no directions register at all. It might be so that I'm using bad transistors or wired something in the wrong way, but I really tried to look up the B, C, E to get them right.

Has anyone else been using these designs? Since I don't have a true Apple II joystick (and these seem to go for the very least $30 each, plus shipping so I didn't order one yet), I can't tell for sure that it is supposed to work but as one out of five joysticks makes the computer to register some kind of fire buttons, even if a cyclic pattern, something is happening?

I might try to restore the adapter to the non-autofire version and troubleshoot more from that state.

 

[Call-151]

Yes, I also made a db9 to db15 adapter using the above circuitry. like you, I can move left right top and bottom, but the buttons did not work... from research, looks like the joystick button need +5v connection as the pc joystick is just a straight thru connection and the pc itself carries the +5v needed to activate the button from 0 to 1. I believe the transistors should be correct, but i may just connect the +5v to the button circuit then to ground and try that before i look into the transistors. Any update on your side?

 

[carlsson]

No, I haven't investigated it further but I thought the Apple also carries +5V so it would be covered? There is more discussion about this adapter in some Usenet or mailing list post that has been uploaded to various sites, but I didn't see any additional notes beyond what the diagram displays.

 

[Call-151]

So I rebuilt the above adapter to the slightly more complex variant to work with autofire joysticks:
http://apple2.org.za/gswv/a2zine/faqs/R030PCA2RF.GIF.

So I gathered all the necessary parts and had time to build the above schematic.. where I am from, the 2N3645 is hard to come by, but I did manage to get a replacement transistor (NTE-129, which is a direct replacement for this transistor). Followed the schematic, checked the wiring and soldering twice, connected it to the IIgs, and all I get is a blinking screen pattern. turned it off after 5 seconds to make sure didn't destroy anything on the computer. Hmm, I wonder if its the transistor, or I may have to recheck the circuit again. If everything checks out, i may just scrap this circuit and go with my original circuit and just connect the buttons directly to +5v. If this fails, i still have my 16pin usb joystick adaptor circuit which i am just waiting for my usb gamepad to arrive from china.

 

[carlsson]

As far as I can tell, the [4] and [5] on the PC joystick side really are GND lines misplaced on the diagram.

Lesson learned: Never question what someone more knowledgeable than you has cooked up. After some thinking and chatting on IRC, it struck me that the PC side pins 4, 5 probably should go to +5V on the Apple side after all, as that is how an Apple joystick would work. So I removed all the other junk, restored the adapter but with the above change. At first, it didn't work any differently but then I noticed one pin on the DIL-16 socket was not inserted properly. After fixing that, I get both directions and at least one of the PC joystick buttons to register as an Apple joystick! Success after two years... I need to investigate the second button, and obtain more software using a joystick now that it works.

So for anyone trying the same: follow the original design, don't make your own assumptions unless you know exactly what you're doing. In this case, the diagram seems perfectly OK as it is published.