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Comment by actionfromafar | Hacker News Reader

The headline is probably wrong, the article text just says "capable of" 16 kilobyte. I also think it's unlikely it had 16 installed. On the other hand, doesn't the screen look like a flatscreen, not a CRT? So the screen itself was probably very expensive in itself. (Probably plasma screen?)

Edit:

Look at the image and the bank of 3 * 8 socketed chips:

https://www.peel.dk/Q1/img/SN615-03.jpg

If these are the Intel 2102 [1] or something similar, then it would have 3 kilobytes of SRAM.

1: https://w140.com/tekwiki/wiki/Intel_2102

Edit 2: the computer in the picture is another model, ignore me.

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Probably not a plasma screen in the 70s. It looks like a bunch of individual characters. They are probably vacuum fluorescent like what was on calculators and the Speak & Spell educational toy from that period.

https://www.thebyteattic.com/p/q1.html

Looks like it is plasma but with characters, not a pure bitmap display.

Yes, it is pretty certain that no bitmap plasma displays existed at that time, because the drivers for them would have been more expensive than an entire desktop computer (due to the high number of rows and columns).

It is said that the display was an unusual plasma display and not a vacuum fluorescent display, which were much more frequent in the desktop calculators of that time, but it must have been an alphanumeric display with segments, perhaps with 16 segments per character.

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.

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.

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.

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.

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.

> 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."

>"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."

Sounds more like it has Bresenham's algorithm implemented in hardware. It would still plot individual pixels on a 512x512 grid, which is different from how an actual vector display draws lines.

Maybe we can agree to disagree about the terminology here. To me if it takes vector inputs and displays them, it doesn't matter if it's pixels on a grid or tiny elves holding up colored signs. It's a vector display.

In any case, the PLATO display absolutely did not use "segments", as the OP claimed that it must have. He also claimed that bit-mapped plasma displays "didn't exist at the time".

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.

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.

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".

Vector. Monitors. Are. Analog.

You are thinking of digital vector GRAPHICS displays with hardware line-drawing support. Analog vector monitors and digital vector graphics raster displays are two different things. Vector monitors can draw nonpixellated curved lines as well as straight lines. Vector monitors can draw lines at any angle without staircasing. If a screen has pixels, it is not a vector monitor.

The 1970s Asteroids arcade game had an analog vector monitor without pixels. Ditto the PDP-1 Spacewar and PDP-11 Lunar Lander, both of which I saw in the 70s. Ditto the Star Wars arcade game. Some vector monitors had rapid-fade phosphors and had to be constantly redrawn, others were bistable storage tubes that retained an image for several minutes without being redrawn. The Plato terminal did not have an analog vector monitor.

https://en.m.wikipedia.org/wiki/Vector_monitor

https://en.m.wikipedia.org/wiki/Star_Wars_(1983_video_game)

https://en.m.wikipedia.org/wiki/Battlezone_(1980_video_game)

https://en.m.wikipedia.org/wiki/Direct-view_bistable_storage...

Ah ok. So maybe one of the early Panaplex segment displays instead of bitmap displays that came later.

From this link posted in another thread, the structure of the display is a little clearer: https://www.peel.dk/Q1/

In the shot of the display frame by itself without the tinted plastic in front of it, it almost looks like a miniature arrival/departure board at a train station.

It appears to be a Burroughs Self-Scan plasma display.

The display in action on a Q1: https://www.1000bit.it/lista/q/q1europe/q1microlite.png

Close-up shot in a Q1: https://www.peel.dk/Q1/img/SN615-05.jpg

Brochure: https://archive.org/details/TNM_Self-Scan_II_panels_for_data...

There are videos of the display being demonstrated on YouTube. Search for Burroughs Self-Scan.

That picture appears to be from a Q1/Lite, which is a different beast (and used 4116 DRAM according to the schematics)

And.. the original article's picture is also a Q1 Lite, as far as I can tell. Introduced 1977. That one used NEC 4116 dynamic RAM. And did not use the 8008.

It's very difficult to find anything about the original Q1. Even the "First Q1 Brochure" from TheByteAttic is actually a Q1 LMC, which was the second model.

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