CD64 Parallel Port Adaptor
Here are a few pictures and a schematic of the CD64 Parallel Port Adaptor
In addition to this adaptor you need a "Straight Thru" Parallel Cable (DB25 to DB25)
On the schematic there is one error that I am aware of, the resistor between Pin 9 on the 74HC74A and Pin One on the CD64 Connector is 220 Ohms, not 10k.
Edit by Ryan: Pin 6 (~Q1) on the 74HC74A is connected to pin 13 (Reset2) of the same chip. This is so that when the busy signal on the PC side is set (by toggling Autofeed, which sets Q1 and thus /BUSY to a low state, but /BUSY is inverted in the hardware) /PCX is also set to low to tell the CD64 that the PC is ready to receive data.
It would probably be easier to buy this adaptor that to build it, but if anyone wants to try, here ya go.
You can purchase the adaptor at: http://126.96.36.199/store.asp?swfprod_id=55