Hewlett-Packard 7221T Plotter User's Manual.
F. S. Durk · 1983
Abstract : This document is a user manual for the Hewlett-Packard HP7221T plotter. The HP7221T uses a compact binary command language. This manual contains a set of FORTRAN '77 utility subroutines written for a PDP 11/24 which makes it easy to generate plots. (Author)