Random Pre-Silicon Ingredients… so it’s all analog without storage…
Tektronix Type 564B Storage Oscilloscope with Plug-In Type 365 Spectrum Analyzer and Type 3A9 Differential Amp
Tektronix 148-M Insertion Test Signal Analyzer
HP 191A TV Waveform Oscilloscope
Tektronix 520A NTSC Vectorscope
Blinking Red Light
So it’s a piece of vintage electronics with a screen and a handful of vacuum tubes. No transistors or memory chips. So how does it “remember” the trace on the screen to show it persistently? From a bitmap perspective on the screen, there is a lot of data to be retained…
The answer is fascinating. Memory is implemented in the display screen itself with a separate tracing beam reading the phosphors and regenerating them with the write beam (Wikipedia details). It reminds me of early computer memory systems that stored data on the phosphor of a CRT…. (giving “Video RAM” a literal instantiation =)
Ranjit: so now that we know how an image can stay on screen, to make an Etch-a-Sketch, you dial the beam down to a point or small bar, and use the vertical and horizontal adjustment knobs to paint with light. It has all the limitations of the original toy (you can’t lift the “pen”) but it does have half-screen erase options…
This is an alpha-stage product, so the flicker on the screen is missing a couple letters. Today, flickr is in gamma, so it’s just missing one letter…. 😉
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