Lawrence LeMay wrote: --snip-- Plato as a project evolved through many stages; when CDC jumped in they began by providing courseware through Cybernet and other hosts using a terminal designed around a plasma display screen which allowed rear-projection of slides and other overlays. The terminal had no intelligence. The machine you describe was a later-stage micro-based implementation which ran CP/M and Plato courseware ported to it as well as MECC and standard CP/M based packages. CDC Literature Distribution (in whatever form it may still exist) should have beaucoup hardware manuals. Michael Grigoni Cybertheque Museum

I'm working from memory, but I believe the original Plato terminals used a non-standard "character" length that was something like 20 bits for receive and 12 bits for transmit. And they were possibly strange rates as well. The "receive character" actually could contain several characters in one "packet". If your's is one of the original, you may find it somewhat problematic to talk to it in a meaningful way <g> My experience with these stems from a short-lived attempt back in about 1974 - I was working on a "second generation" terminal mux for our home-grown timesharing system at Oregon State, and the computer center had (if I recall) three of the Plato terminals (which were normally used via modem to the system in Urbana, IL). The "powers that be" decided they wanted to connect them to the local t.s. system and it became "my job" to find out how. It was not an easy fit and we gave up after a few months of trying to coax the mux into producing and receiving with the right framing characteristics. But I did have to learn (but quickly forgot) the weirdness of the communication protocol. By the way, a while back I obtained a plasma display unit from an old Plato terminal (512x512 neon plasma display with "see through" rear-projection screen. I also found the Owens-Illinois technical manuals for this unit and was wondering if it is the same display as in the original Plato terminals. If so, I could make copies for you. The manuals I have are: UM607 - DigiVue User Manual 512-60 Display D141 MM608 - DigiVue Maintenance Manual 512-60 Display D141 UM609 - DigiVue User Manual 512-60 Power Pack S159 / S205 MM610 - DigiVue Maintenance Manual 512-60 Power Pack S159 / S205 Someday I need to make a controller and fire mine up so I can play with it. Takes all sorts of power supplies (I have just the display - not the power pack) but the interface is pretty simple. It uses a 30 pin data connection whose inputs are X,Y position, write/erase/sync and some other misc control and status lines. They were really cool displays for their time. Gary At 09:46 PM 1/29/99 -0600, you wrote: