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Terminals like the VT220 were much more expensive because they needed much higher bandwidth analog electronics than conventional TV circuitry (the limit isn't o
by yodon 7y ago
Terminals like the VT220 were much more expensive because they needed much higher bandwidth analog electronics than conventional TV circuitry (the limit isn't on the B/W tube, it's on the electronics that steer the beam around)
- tyingq 7y agoI think there's not much difference in the horizontal/vertical driver circuits. Here's the (pretty pedestrian and likely not different from a b/w tv) diagram of the horizontal driver for a vt220: https://imgur.com/a/xvq1ukV https://imgur.com/a/xvq1ukV The shown MC1391P is, in fact, called a "horizontal TV processor" by Motorola. I'm sure there's other stuff that made them expensive (CPU, memory, video logic, etc). Edit: Lol at imgur for marking my screenshot as "erotic" and NSFW.
- yodon 7y agoAwesome find. That said I think the bandwidth issue was less with the semiconductor electronics in that diagram and more with the big analog electronics that actually controlled the gun directly (the box labeled horizontal driver in your image)
- tyingq 7y agoHere's the other two boxes: https://imgur.com/a/yJH9QYu https://imgur.com/a/yJH9QYu (Which Imgur also finds erotic and NSFW. Odd)