Changes

* Printer data-bits are connected to AY I/O port B (PSG register 15). * Printer strobe is connected to PPI 8255 port C bit 4. The strobe is negated by the hardware.* Printer busy is connected to PPI 8255 port B bit 6.* All of the above PPI and PSG registers are bi-directional. This is different as that in the CPC (the CPCs [[Printer Port]] uses Port EFXXh for one-directional 7bit data plus strobe).