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dmytrish | 2 years ago

Yes, but even UART could handle some kind of a simple multiplexer protocol with multiple data streams.

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rbanffy|2 years ago

It's the OS's job to expose a stream interface on top of a UART.

There was a graphical terminal called the Blit (sold as the AT&T 5620, succeeded by the DMD 630 and then the 730 "Multi-Tasking Graphical Terminals"). They implemented windowing, multiple streams, graphics and a lot more on top of serial connections. Essentially, multiplexing streams on top of "a UART". What you describe is more or less what they did back then, minus the windowing and multi-tasking functions, because we let the host OS deal with that.

There is even a neat 5620 emulator for macOS you can download from the app store. It requires a proprietary shell running for that tty, and I never took the time to figure out exactly how it works.

https://archives.loomcom.com/3b2/documents/DMD_Terminal/ has some good docs on that, and bitsavers.org has a ton more on the 630 and 730.

I hope one day someone finds a ton of them forgotten in a warehouse in the middle of a desert in the US, because, where I live people recycle old computers with an uncanny dedication (those barbarians!).

rigid|2 years ago

which would be in-band signalling again since uart is just timed 0's and 1's over a single tx and rx signal.