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What we think of as "plasma screens" were invented at UIUC for the PLATO project in (checks) 1964, by Donald Bitzer, H. Gene Slottow, and Robert Willson. They h

What we think of as "plasma screens" were invented at UIUC for the PLATO project in (checks) 1964, by Donald Bitzer, H. Gene Slottow, and Robert Willson. They had a resolution of 512x512. They started cranking them out in bulk in 1972. These were monochrome orange vector displays. They didn't use segments.

adrian_b 3y ago
Wikipedia says that the 512x512 PLATO plasma display had a cost of $2500 at a time when that was a much greater value than today. Moreover, I doubt that the cost includes the one thousand high voltage transistors that would have been needed to drive the display. As I have already written, such a display would have been too expensive for a desktop computer with an 8-bit CPU. In the early seventies, as an alternative to the red LED displays and green or blue vacuum fluorescent displays, there were the orange Panaplex plasma displays with segments for numeric (7 segments) or alphanumeric (14 or 16 segments) characters. I believe that the Q1 computer must have had such a Panaplex display, which was cheap enough. Vector displays are possible only where there is a drawing spot that can be moved in any programmable direction, i.e. only on CRTs or mechanical plotters. They are not possible with plasma displays.
- jjtheblunt 3y ago
  Where did you get the 1000 high voltage transistors thing? I used PLATO at UIUC in the late 80s briefly, because they were still around, but everything had been WYSE-50 or Sun already (or contemporaries) and the PLATO terminals weren't some monstrosities....just looked 20 years old.
  - adrian_b 3y ago
    In the simplest case you need one transistor per row and one per column for bitmap displays. If any transistor in omitted, than that row or column must have a fixed voltage, which means that the corresponding column or row of pixels would no longer be controllable and they would display the same pixels as whatever other column or row is selected at a given instant. One thousand transistors do not need a huge space (they would fit easily on a PCB of a size compatible with a PLATO terminal, based on the photo from Wikipedia), but they were quite expensive. Suitable high-voltage integrated circuits have appeared later. In 1972, one could have used Nixie decoders like 74141 for the negative voltage, replacing 512 transistors with 64 IC packages, but 512 discrete transistors would still have been needed for the positive voltage. For segmented alphanumeric displays you need only 14 or 16 transistors for the segments plus one transistor per character.
    - BizarroLand 3y ago
      Probably better to use a mux/demux system rather than 1 transistor per segment. You can build a system to control a large binary system with simple relays and gates and a comparatively few transistors. Given that they did much more work with relays back then, in absence of a better idea I would pin my bets on that.
- Turing_Machine 3y ago
  > As I have already written, such a display would have been too expensive for a desktop computer with an 8-bit CPU. They were subsidized to some extent, but they were nonetheless cranked out by the hundreds. > Vector displays are possible only where there is a drawing spot that can be moved in any programmable direction, i.e. only on CRTs or mechanical plotters. They are not possible with plasma displays. I'm sorry, you are simply wrong here. The Plato display did have vector graphics. Your own Wikipedia citation disagrees with you: "The display was a 512×512 bitmap, with both character and vector plotting done by hardwired logic. It included fast vector line drawing capability, and ran at 1260 baud, rendering 60 lines or 180 characters per second."
  - ahazred8ta 3y ago
    A vector display is a non-pixel-based screen like a radar screen or oscilloscope. I used a vector computer terminal in 1979. I also used a Plato, which did have vector graphics but was not a vector display.
    - Turing_Machine 3y ago
      No, a vector display is one that takes vectors as input and displays them. What happens inside the display is irrelevant. PLATO used this type of display because it was running over very slow dialup modems, and vectors, while having their limitations, are much more compact than rasters. Example: suppose you want to draw a line on the 512x512 PLATO display. With a raster method, you have to send 512x512x(number of brightness levels) down the pipe. With a vector display, you only have to send DRAW(X1,Y1,X2,Y2) or (equivalently) DRAW(X,Y,length, angle) 5 numbers versus hundreds of thousands. The PLATO display had direct hardware support for line-drawing commands. That made it a vector display.
      - rep_lodsb 3y ago
        A vector display is not the same thing as a vector format for storing/transmitting graphics. On a raster display (what we all have today), a line must be made up of discrete pixels, whereas on a vector display, there is an analog integrator that moves the X/Y deflection smoothly between the endpoints. This might not matter if you have a high resolution, multiple brightness levels, and a CPU/GPU powerful enough to do antialiasing, but for 512x512x1bpp the pixels making up each line will be very visible as "stairsteps".

adrian_b 3y ago

Wikipedia says that the 512x512 PLATO plasma display had a cost of $2500 at a time when that was a much greater value than today. Moreover, I doubt that the cost includes the one thousand high voltage transistors that would have been needed to drive the display. As I have already written, such a display would have been too expensive for a desktop computer with an 8-bit CPU. In the early seventies, as an alternative to the red LED displays and green or blue vacuum fluorescent displays, there were the orange Panaplex plasma displays with segments for numeric (7 segments) or alphanumeric (14 or 16 segments) characters. I believe that the Q1 computer must have had such a Panaplex display, which was cheap enough. Vector displays are possible only where there is a drawing spot that can be moved in any programmable direction, i.e. only on CRTs or mechanical plotters. They are not possible with plasma displays.

jjtheblunt 3y ago
Where did you get the 1000 high voltage transistors thing? I used PLATO at UIUC in the late 80s briefly, because they were still around, but everything had been WYSE-50 or Sun already (or contemporaries) and the PLATO terminals weren't some monstrosities....just looked 20 years old.
- adrian_b 3y ago
  In the simplest case you need one transistor per row and one per column for bitmap displays. If any transistor in omitted, than that row or column must have a fixed voltage, which means that the corresponding column or row of pixels would no longer be controllable and they would display the same pixels as whatever other column or row is selected at a given instant. One thousand transistors do not need a huge space (they would fit easily on a PCB of a size compatible with a PLATO terminal, based on the photo from Wikipedia), but they were quite expensive. Suitable high-voltage integrated circuits have appeared later. In 1972, one could have used Nixie decoders like 74141 for the negative voltage, replacing 512 transistors with 64 IC packages, but 512 discrete transistors would still have been needed for the positive voltage. For segmented alphanumeric displays you need only 14 or 16 transistors for the segments plus one transistor per character.
  - BizarroLand 3y ago
    Probably better to use a mux/demux system rather than 1 transistor per segment. You can build a system to control a large binary system with simple relays and gates and a comparatively few transistors. Given that they did much more work with relays back then, in absence of a better idea I would pin my bets on that.
Turing_Machine 3y ago
> As I have already written, such a display would have been too expensive for a desktop computer with an 8-bit CPU. They were subsidized to some extent, but they were nonetheless cranked out by the hundreds. > Vector displays are possible only where there is a drawing spot that can be moved in any programmable direction, i.e. only on CRTs or mechanical plotters. They are not possible with plasma displays. I'm sorry, you are simply wrong here. The Plato display did have vector graphics. Your own Wikipedia citation disagrees with you: "The display was a 512×512 bitmap, with both character and vector plotting done by hardwired logic. It included fast vector line drawing capability, and ran at 1260 baud, rendering 60 lines or 180 characters per second."
- ahazred8ta 3y ago
  A vector display is a non-pixel-based screen like a radar screen or oscilloscope. I used a vector computer terminal in 1979. I also used a Plato, which did have vector graphics but was not a vector display.
  - Turing_Machine 3y ago
    No, a vector display is one that takes vectors as input and displays them. What happens inside the display is irrelevant. PLATO used this type of display because it was running over very slow dialup modems, and vectors, while having their limitations, are much more compact than rasters. Example: suppose you want to draw a line on the 512x512 PLATO display. With a raster method, you have to send 512x512x(number of brightness levels) down the pipe. With a vector display, you only have to send DRAW(X1,Y1,X2,Y2) or (equivalently) DRAW(X,Y,length, angle) 5 numbers versus hundreds of thousands. The PLATO display had direct hardware support for line-drawing commands. That made it a vector display.
    - rep_lodsb 3y ago
      A vector display is not the same thing as a vector format for storing/transmitting graphics. On a raster display (what we all have today), a line must be made up of discrete pixels, whereas on a vector display, there is an analog integrator that moves the X/Y deflection smoothly between the endpoints. This might not matter if you have a high resolution, multiple brightness levels, and a CPU/GPU powerful enough to do antialiasing, but for 512x512x1bpp the pixels making up each line will be very visible as "stairsteps".