The Parallel Port – 1284 Protocol

This is a brief and hopefully concise description (not a specification) of the IEEE 1284 protocol and its signal timing as used by computers to communicate with parallel port (Centronics) devices.

The reason for writing this is that I found no such information when I wanted to build a special network device using the parallel port. Information was either not freely available, or was incomplete and wrong. Also, all documentation was unclear in some way or another. I had to use this flawy documentation while reading the source code of the Linux kernel driver in parallel to implement the protocol correctly.

I have only documented what I have tested and implemented myself. There are many other 1284 modes that need to be documented.For reading the Linux kernel parport/lp driver, download the Linux kernel. If you are really serious about this: the standard can be bought from the IEEE.

Although I try to provide useful information, I cannot guarantee that all my findings are correct. You cannot blame me if anything goes wrong.

All disputes shall be settled in Germany at Saarbrücken City Court.