LSI-11 question

From: Eric Smith <>
Date: Sat Mar 20 00:36:52 1999

> What was a GT40?

A graphics terminal based on the small (5.5 inch tall) PDP-11/05
minicomputer, with a VR14 vector display (14-inch magnetically deflected
X-Y monitor), a keyboard, and a light pen.

The display list processor of the GT40 is a three-board set, referred to
in some of the documentation as a VT40. The same boards in a different
backplane were available for use on other Unibus systems as a VT11.

The display list processor has a boot PROM that makes the GT40 act as a
dumb terminal, and supports downloading of executables over the serial line
from the host in a special format. (Unfortunately the actual boot PROM in
my GT40 doesn't match the listing in the manual; in fact it's not even

> I was asked recently to comment on a system
> which originally used a VT05 and then a VT52. I actually kept a
> working VT52. What was a VT05? Or at least what were the
> differences between a VT05 and a VT52?

The VT05 was the first raster CRT terminal DEC made in-house. It is not as
tall as a VT52, but a little deeper (which is amazing as the VT52 is quite
deep). The styling was that early-1970s "futuristic" styling. If memory
serves, it has only 12 lines of display, and is fairly "dumb". By comparison,
the VT52 or the classic ADM-3 dumb terminal is genius-class.

> Also, as far as I know, the VT11 support was still present in V5.4G
> of RT-11.

At least some of it.

> Mentec has access to V5.3 of RT-11. Actually, everyone who wants
> to run V5.3 of RT-11 under a hobby license with the Supnik emulator
> can download V5.3 from gatekeeper.

Unfortunately this license does not allow me to use the software on
my GT40. If I added VT11 simulation to Supnik's emulator, at least I
could run it on a simulated GT40. :-)

I'm hoping to be able to demonstrate the GT40 at the upcoming
Vintage Computer Festival. However, since I don't have an operating
system to run on it, I will only be able to load one game into core
and leave it running. I'd hoped to be able to set up a menu program
that would load other games from a disk, but I'm not going to go the
all the trouble of doing that without an operating system.

Received on Sat Mar 20 1999 - 00:36:52 GMT

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