Great and simple write-up. Vaguely remembered nycresistor from other articles I've read, so I'm glad this was posted here.<p>I think HN would be well served to have more front page retro hardware hacking articles. They may not be useful in the same way as other posts, but they sure as heck are delicious brain food and a relaxing diversion.
Plotters are just one small step removed from a 2D mill. This particular kind of plotter, where the paper is fed through to obtain one axis of movement suffers from bad registration, any kind of slippage on the paper (and there always will be some) will lead to registration errors. Try different kinds of paper to determine which kind gives you the least slippage by repeatedly drawing very large patterns in different colors and then studying the horizontal edges near the limits.<p>The command set looks like a modified HPGL.
Since OP mentioned the nice big HP x,y plotters, that reminds me I once wrote an emacs lisp HPGL driver to hit the serial port and run one in grad school. I'll have to dig it up sometime.<p>Edit, just remembered: it was probably to output one of the VLSI CAD layer formats, like GDS or EDIF.
I really should find mine. I got it for free off of a local computer store's junk table about 12 years ago. My understanding is that it's fairly uncommon, at least compared to the Imagewriter I/II. Would be cool to take the roms and try to write an emulator for it, though I think emulating the Laserwriter would be more valuable from a historical perspective, since it was so influential in desktop publishing (and one of those odd cases were the peripheral had a faster CPU than the computer it was connected to, much like the Commodore 1541 disk drive).<p>Edit: And on second glance it's quite possible that 410's Z80 is clocked faster than the 6502 in the Apple II.
The simple plotters of the past were really great pieces of kit; and fun as the day is long.<p>Even the little Commodore 1520 was a very capable machine in a toy form factor. Four independent color pens, and a great tool for learning geometry and programming at the same time.