The timing on the #TRS80CoCo leaves me a very narrow window to return data. I'm not quite sure how we managed to make the MSX #FujiNet prototype work, and yet it does. I'm going to have to see if I can optimize my code even more on the #RaspberryPi Pico to be able to return the data sooner.

#RetroComputing #VintageComputing

Setup a couple of GPIOs for debugging. When my routine is called it flips D2 on at entry and off at exit. D3 is toggled each time the write routine is called (POKE &HFF42,val). I can see that the routine was called 32 times and wrote 32 bytes (16 rising + 16 falling). Yet only 21 of 32 bytes were transmitted. #TRS80CoCo #FujiNet #RaspberryPi #RetroComputing #VintageComputing
I was overflowing the FIFO! Doubling the clock speed of the Pico to 250MHz got it working. Well, after adding another wait to the PIO routine. #TRS80CoCo #FujiNet #RaspberryPi #RetroComputing #VintageComputing