Foxie wrote:And in fact, is it implemented in the FPGA yet? I heard the cartridge port isn't implemented yet despite the pin header being present.
mfro wrote:Regarding 5V tolerance: the port does not have dedicated level shifters, but uses the (Altera recommended) 5V adaption 'trick' using a resistor and the built-in PCI clamp diodes of the FPGA.
IMHO, this should be safe. There is a small risk, however, as the PCI clamps only get active once the FPGA configuration is loaded (which takes a few seconds after power-on). I did not see any damage during my tests, but decided to disconnect the printer after that (I don't need it anyway), so I can't provide long term experience.
mfro wrote:In theory, the port should just work as it does on an original ST. Just several magnitudes faster - required us to insert busy waits into EmuTOS and FreeMiNT parallel port drivers to slow it down to IEEE standardised strobe timing (busy waits are missing in FireTOS which is the reason printing will not work there).
Foxie wrote:So the 625ns YM access delay has been eliminated? Which method did you use to slow the strobes down? I'd rather not dedicate an entire MFP timer to the task, perhaps a calibrated delay loop is viable?
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