Rtekpen for the Raster Tech 1-10, 1-75, and 1-80.

POLYGN command on the rastertek defective. Genpatarea used instead.

Flushing is done whenever an entire command will not fit in the remainder
of the buffer. This is because the DMA for the Rtek is buggy and overruns
the end of the file. The end of the file is padded with NOP's so that no
harm comes from the extra garbage sent along.

Author Rick Ottolini, with some touching up by Stew Levin and Joe Dellinger
