That's not completely straightforward, because the MMFS user port driver uses the 6522 shift register for bulk data transfers, where the clock is generated from CB1. That assignment can't be changed. Using the shift-register mode provides a considerable speedup.If possible, it would be great to have a official MMFS release made for this hardware design. It would allow Compact users to have their Joystick port free for the mouse even when using MMFS...
The only way to change the pinout would be to write a new "driver" that bit-bangs all the signals. There is already an example of this, the Beeb Printer Port Driver, which bit-bangs via Port A (MOSI = PA0, SCK = PA1, MISO = PA7). This could be adapted to use Port B (MOSI = PB5, SCK = PB6, MISO = PB7). But the code would have to change a bit, and would likely be slightly slower.
The bottom line is I think it's possible.
Do you have prototype hardware yet?
Dave
Statistics: Posted by hoglet — Wed Nov 13, 2024 11:24 am