prindle@NADC.ARPA (08/17/84)
Apparently, much of the traffic on net.micro.cbm never makes it to the ARPANET, because I never saw the original article. But anyway, the C64 joystick trigger button doesn't interrupt the cpu (it does toggle a line on the VIC chip which causes the VIC chip to save the light pen raster coordinates). Furthermore, the joystick ports are only 5 bits each and are shared with the keyboard scan ports (contol port 1 is 5 rows of keyboard in, control port 2 is 5 columns of keyboard out scan), so the keyboard scan would have to be disabled in the kernel before you could assume complete control over these ports. I don't know what kind of D to A conversion was required, but 5 bits only gives 32 possible analog levels. Does anyone know why ARPANET coverage of net.micro.cbm seems so sporadic? Frank Prindle Prindle@NADC.ARPA