15 Apr
2014
15 Apr
'14
2:49 p.m.
On 04/15/2014 02:16 PM, Paul Koning wrote:
Excellent. I
wasn't aware cyber1.org had a way to handle the 19/10 bit
frames. This gives me incentive. Since I need to build hardware in any
case to handle the keyboard and data to the display (as I said, I
received NO additional hardware) it should be simple enough to just do
some appropriate conversion to TCP/IP there as well and give it an
ethernet connection (l'll likely use a Beaglebone for the task. Kinda
overkill, but easy.)
Thanks for the info. I will research this project further.
-Gary
On Apr 15, 2014, at 4:50 PM, Gary Oliver <go at
aerodesic.com> wrote:
Magnavox sounds familiar. Our terminal was in a large sheet-metal box
without a micro I'm sure, given the time-frame (mid 1970s.) I looked at
the manuals on bitsavers, but they seem to refer to the video-terminal
variety.
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.
I know our terminal
DID NOT speak ASCII, as the reason I had access to
the terminal was to evaluate creation of software on our front-end
processor for interfacing the beasties to our home-grown operating
system. When the hardware department found they would need to build
some stuff to make this happen, interest waned. This was back when I
was a student at Oregon State, working in the systems programming
department at the computer center.
-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.
No slide projector,
alas, though I saw an electrically operated remote
control one go through our local Goodwill recently - perhaps I should
snag it if it's still there. I could certainly build the necessary bits
to interface it. And thanks for the pointer to the GSW.
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