FLOPPY DRIVE EMULATOR FOR OLD COMPUTER SOFTWARE
You can get the content of floppies with the software X-Copy you find in the software package (see above the software section, there is a video too). To know more about MFM coding anyway and other useful stuff here there are lot of infos. So if between 2 zeros there are 4 us, the system recognizes a '10' sequence (the line is inverted), if there are 6 us the system recognizes a '100' sequence and if there are 8 us the system recognize '1000', as it's the MFM coding. The approach in this case was to take the times between the 0 cells (on the falling edge) and use these to obtain the data stream. For the data in input, the DKWD line, indeed it was not possible to use SDI because without a clock or a PLL, errors will appear soon. In order to have a better shape for the DKRD line, the signal should stay low for less than 2 us (400ns should be good) so the signal was 'reshaped' by the resistor R15, the capacitor C3 and the diode D6, improving the compatibility with the Amiga software (really only few games are sensible to this timing).
FLOPPY DRIVE EMULATOR FOR OLD COMPUTER FULL
In order to manage the DKRD line (disk read) and have a full stream of data with exact timing (2us per cell) sent without any interruptions,holes or delays, the software uses the SPI interface in continuous mode: all the MFM data goes through the SDO pin while other SPI pins are not used and they are configured and treated as standard GPIO.
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