The Hewlett-Packard 7475A is a 6-pen plotter from 1983. It can draw on either A3- or A4-sized paper and speaks HP-GL over an RS232 serial port. These things are really cool to watch while in action and are practically indestructible.
I wrote a tiny Python script, hpglplot, to plot HP-GL files on this plotter using software handshaking (so you can use a simple three-wire serial cable without any problems).
- HP 7475A Technical data (PDF, 60kB)
- HP 7475A Operation and interconnection manual (PDF, 1MB)
- HP 7475A Interfacing and programming manual (PDF, 3MB)
- HP 7475A Service manual (PDF, 1MB)
- Cenon (a useful multi-platform program for converting various vector formats into HP-GL)