Parallel Port Query

Does anybody have information of how the parallel port on the old Atari ST compares with the parallel port of modern PC's?

I'm running an app on an emulated PC, which runs fine, apart from not printing hardcopies of documents produced!
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  1. Probably uses a different interface. Nevermind that most emulators don't worry too much about the parallel ports...

    The serial port is standard RS-232. The parallel port was the "Centronics Connector".

    Centronics parallel is generally compliant with IEEE 1284 compatibility mode. The original Centronics implementation called for the busy lead to toggle with each received line of data (busy by line), whereas IEEE 1284 calls for busy to toggle with each received character (busy by character). Some host systems or print servers may use a strobe signal with a relatively low voltage output or a fast toggle. Any of these issues might cause no or intermittent printing, missing or repeated characters or garbage printing. Some printer models may have a switch or setting to set busy by character; others may require a handshake adapter.
  2. There are different versions of the parallel port. The standard parallel port (SPP) and the bi-directional variant: the enhance parallel port (EPP) and the extended capabilities port (ECP)

    For plain parallel port (SPP) printing be sure you have lpt1 setup on irq7 address 0378. You would need this to match in the bios as well as your software. Actually the bios you will need to set the port type also (SPP, EPP, ECP).

    If that doesnt work, early IBM PC's used 03BC instead of 0378. I'm not sure if you'de be able to configure the bios to that address.

    Lastly, you may need to configure the printer to emulate an SPP printer rather than an bi-directional one.
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