This is a collection of software for the DEC GT40 Graphic Display Terminal,
which is a dual-processor vector-graphic device.

The GT40 is composed of one of the later PDP11s (with real core memory!) plus
a vector processor that has its own strange instruction set whose side-effect
is to move the beam on a cathode ray tube.

To make a display, the PDP11 program has to write some GT40 code into core then
write the start address of this "graphic program" into the vector processor's
program counter. The graphic processor then executes this, creating an image
on the screen, while theh PDP-11 goes on its way to generate the next "frame".
Thus the GT40 code for most static displays is composed of a sequence of
drawing operations followed by a jump back to the beginning of the same code.

The device also had a light-pen interface that could trigger when the cathode
ray passed it. (see pdpasm/follow.11)

gtload.c	Translates a PDP11 object code file into GT40 download format
		ready to be sent to it over a serial cable.
gtqvtap		Object code, though I don't know what it does.
lander		Object code for the Moon Lander game.
lander.ld	Moon lander code translated into download format.
pdpasm		My own PDP11 test programs for the GT40.
pdpasm.jd	Jim Darby's port of the BCPL code generator and assembler to
		the PDP11/GT40.

	Martin Guy, 29 Oct 2005