http://en.wikipedia.org/wiki/Parallel_port
Nibble and byte reverse transfers are done by clicking on any SEND button. Same for ECP modes.
The PC's parallel port can't be used to emulate a printer: the laplink and ECP link cable can't route the needed signals. So I developed a printer emulator running on a Gameboy Advance SP equipped with the Xport board from Charmed Labs. For convenience, I made a PCB for easily connecting the GBA to a PC. The PCB Gerber files are available here and are ready for BatchPCB (or other fab).
This emulator implements the negotiation phase and SPP, nibble, byte, ECP, ECP RLE
modes. The EPP mode is not supported.
It has been a while since I've done the printer emulator. My setup with the PCB doesn't work anymore with my new PC, and compatibility mode never worked. However, the other modes worked up until recently, when I changed my development PC.
I ported the printer emulator to the mbed platform, which is faster than the Gameboy Advance.
http://mbed.org/users/jpelletier/programs/Printer_emulator