ccsoola@sacemnet.af.mil (CCSOOLA) (11/25/90)
Quoting from message <15998@cbmvax.commodore.com> by Bob Raible <raible@cbmvax.commodore.com>: > The following are directions for converting the Atari trakball that has > no testpoints and no socketed IC's as previously described. [Other identification info omitted...] > ...on left side of [the trackball's] PCB are 2 IC's.... Topmost IC I'll > label IC#1 (16 pins).... [Other instructions omitted...] > 3) Connect port pin #1 to IC#1,pin #6. > Connect port pin #2 to IC#1,pin #10. > Connect port pin #3 to IC#2,pin #11. > Connect port pin #4 to IC#2,pin #3. > > This serves to hook up mouse vertical and horizontal, and > their quadratures(in that order). [Further instructions omitted...] I followed the instructions to the letter, and the trackball conversion _mostly_ worked. I couldn't get any coherent movement in the horizontal axis, though, so I had to fiddle with it. I wound up making one change to the above instructions: Instead of "Connect port pin #2 to IC#1,pin #10." try "Connect port pin #2 to IC#1,pin #2." When I did this, the x-axis worked. (I'm not sure just what I've hooked into; I don't have pinouts for IC#1, but I traced signals with a logic probe until I found something likely-looking. When I did, I tried the connection described above, and it's hunky-dorey.) >JS< +-------------------------------------------------------------------------+ | John L. Schuncke, Jr. | "I wanted to say something completely | | CCSOOLA@SACEMNET.AF.MIL | mindless, but now I can't think of it." | | Staff Sergeant, USAF +------------------------------------------+ | Command and Control Systems Center, Operating Location "A" | | Offutt AFB, Nebraska | +-------------------------------------------------------------------------+ | Standard Meaningless Disclaimer: The opinions and policies expressed | | in the above electronic communication are those of its author ONLY. | | (As if anyone else would have them!) | +-------------------------------------------------------------------------+