From: James Knott via Talk <talk@lists.gtalug.org>
We didn't have any Wyse terminals, mostly DEC & Data Generals, though we also had a bunch on Ontel smart terminals, which, IIRC, were made in Canada. I also used to work on some really dumb (retarded? 😉) terminals that had absolutely no smarts and relied on a Data General Nova to do simple text editing, etc.. These were so old they used an acoustic delay line for memory!
All I can find about Ontel seems to be about smart terminals, like the OP-1. You must have had an earlier model. To use an acoustic delay line, they must have been really really old. You would know better than I because you repaired them. I remember IBM 2260 display terminals. A bank of them was driven by one controller. The controller used an acoustic delay line for the screen memory. (I had always been told that it was a magneto-restrictive delay line, but Wikipedia says otherwise). This terminal system was introduced in 1964, before IBM used integrated circuits. <https://en.wikipedia.org/wiki/IBM_2260> By the time that "glass TTYs" came on the scene, ICs were available and other forms of memory were used. I remember getting a large shift-register memory from a Datapoint terminal (the Intel 8008 architecture matches the Datapoint 2200's processor). Remember that a dumb terminal only needed 24 x 80 characters of buffer. Now we expect bit-mapped displays -- much larger frame buffers. Those display architectures were held back by memory costs. I used a Tektronix terminal on a PDP-8/i (1968/1969). It used a storage CRT so that it didn't need to have a buffer! It felt a bit like using an e-ink display because the whole screen had to be rewritten to make a change (additions didn't require a refresh). The PDP-8/i software was written for a teletype, so basically the user would clear the screen when it filled up -- sort of like putting a new piece of paper in a teletype.