This adapter allows a 15-pin PC joystick to connect to an Apple II series computer's 9-pin games port for X, Y, button #0 and button #1 inputs. There is also space to have a DIL 16-pin header installed for connection to an internal DIL games port in the original Apple II without the external 9-pin games port. Please note that neither the DIL header nor the cable assembly is included.
This adaptor allows a cheaper and plentiful 15-pin PC joystick to be connected to an Apple II's 9-pin games port. It has separate X/Y potentiometers to adjust for the range between 0 and 255. All the Apple II series computers may be used such as IIe, IIc and IIGS. A small onboard LED confirms that power is available.
If the joystick is self-centering at the midpoint, the value should be around 125 for both X and Y coordinates. Actual values depend on the joystick's own setting, Apple II's port reading and the game's interpretation. The random few games tested to be working are Galaxian, Alien Typhoon, Apple Invader, etc.
The following sample Applesoft program allows the connected joystick to be calibrated using the two trim pots on the unit.
20 FOR I=1 TO 10: NEXT
40 PRINT "X: " X " SW: ";
50 IF PEEK(49249) <= 127 THEN PRINT "0";
60 IF PEEK(49249) > 127 THEN PRINT "1";
70 PRINT ", Y: " Y " SW: " ;
80 IF PEEK(49250) <= 127 THEN PRINT "0";
90 IF PEEK(49250) > 127 THEN PRINT "1";
110 GOTO 10