On 04/24/2018 01:33 PM, D. Hugh Redelmeier via talk wrote:
| From: James Knott via talk <talk@gtalug.org>
| However, that system was based on a Data | General Nova 800 and used on dumb terminals (made by VST) that used | delay line memory.
Video terminal "VDT" development was very much gated by developments of memory technology. CRTs need constant refresh so there needs to be some kind of backing store for the image.
Many different solutions were developed.
As I mentioned, the VST terminals used an a delay line. This was a coil of wire, with the signal inserted at one end and retrieved at the other. There was an adjustment for the position of the sensor, to adjust the total delay. The only operations that could be done directly on the stored data was to insert or delete a single character. Anything beyond that required reading and rewriting the display. This involved sending the data to the Nova 800, where the operation was performed, and back to the terminal. In that office, there was another system, based on a PDP-8i and Phillips terminals. Those terminals used core memory.
Now GPU cards come with 4G or more of RAM!
My first video card, in my IMSAI 8080, came with 512 bytes! I soon increased it to a whopping 1K. ;-)