I think there is a software called IBMouse.prg , that will do the same as the p2am. I tried it...works fine. on all modem or serial ports all you need is 25 to 9 pin adapter. standerd IBM .
NOTE the software HSmodem5 will need to be adjusted (remove serial software from port you wish to use :)
if you want to use a ps2mouse you need a 25 to 9 pin serial adaptor IBM standerd and a 9pin serial to ps2 adaptor. I found a 25 pin serial to ps2 adaptor ..stf/stfm/mega.
the MEGAste and the TT has 4 ports all 9 pin.. no adaptor ...sorry no USB software.
you can run a ibm mouse and a atari mouse at the same time ..for the 2 fisted user.
have fun.
ps/2 mouse or serial mouse new
