15 Apr
2014
15 Apr
'14
2:16 p.m.
On Apr 15, 2014, at 4:50 PM, Gary Oliver <go at aerodesic.com> wrote:
I have the 'guts' to the earlier Plato
terminal (the one with the
512x512 plasma.) By 'guts', I mean the keyboard and display - no box or
electronics.
These were picked up from Godbout, I think (way back when...) The
terminal itself had been damaged significantly enough to render the rest
of the electronics unusable - they were not part of the sale. I picked
up the display and keyboard thinking I would someday 'do something with it.'
Fortunately, I did later obtain the four documents describing how the
plasma worked, with connection information, etc. It's basically a
512x512 one-bit-word memory with some special functions. Since there is
a resurrection (of sorts) in an interest in Plato, I thought it might be
interesting to put this beast back together, using some modern
uProcessor to control it, with the end result making it work (from the
serial port) like the old system. I *do* realize the original Plato
terminals were 'strange' with non-8 bit characters in the data pathways.
1) Does enough information exist to do this? I've checked on bitsavers
and find the II and III manuals, but nothing regarding the earlier device.
By II and III did you mean the CDC IST terminals?
There are some PLATO documents on Bitsavers under University of Illinois, but not the
terminal documents. I have a copy of X-50, which is the PPT (?Plato V?) manual, the small
box with wooden sides that had an 8080 in it to run the display. I also have somewhere a
copy of the PLATO IV (?Magnavox?) terminal manual, which is the larger ones with a sheet
metal enclosure, and about 12 cards of hardwired logic, no micrprocessor. Both manuals
describe operation and give full schematics. Both are 512x512 plasma displays.
Yes, these are non-ASCII, they are fed by a stream of 19 bit words, 1200 (or 1260) bps
synchronous.
There are versions of the PPT which speak the ASCII version of the PLATO protocol; that?s
a ROM change. I have such a terminal but no documentation.
-and-
2) Does this even make sense? Would one of these connected to the
"Plato Network" vie TCP/IP be able to do the stuff it could do native
(e.g. control the music synth, slide projector, etc.)
Yes, it could be connected. The ASCII version is very easy to connect. The classic (19
bit) one would take a little hardware to turn the TCP data stream into the correctly
framed synchronous data to the terminal (and to accept the 10 bit asynchronous terminal
output for transmission over TCP). So it could certainly work with the cyber1.org
system.
I don?t remember if the slide projector works with a PPT; I?m pretty sure a GSW (music
box) does not. Both would work with a Magnavox terminal. Both could work with your own
electronics if you supply the appropriate outputs; the interfacing is quite simple.
Finding a slide projector would be an interesting project (or do you have one? If so, do
NOT lose it!). A GSW can be built; if you look up US Patent 4,206,675 you?ll find the
full schematics.
It's been siting in my 'todo' box for 30+ years. Thought I should
eventually do something with it. They were REALLY NEAT displays.
Indeed.
paul