|This article does not cite any sources. (January 2007)|
The HP 7470 was a small low-cost desktop pen plotter introduced by Hewlett Packard's San Diego division. It used a revolutionary "grit wheel" design which moved the paper held in place by a wheel with embedded grit and a pinch roller. The HP 7470 had only two pens, one on either side. It was much less expensive than the previous flatbed design, though by many people's accounts much cooler. It was very heavy but had 4 pens. The HP 7475 used a rotating carousel with six pens. That plotter was used in greeting card kiosks. This design was also scaled up for very large pen plotters. These were driven by the HP-GL plotter language which used ASCII commands such as PA 300, 4500;PD;
Pen plotters became obsolete with the adoption of ink-jet printers, and processors fast enough to rasterize complex images. Houston Instrument and other manufacturers would follow with similar plotters.