You had to tell it when to change lines, when to start firing on a new line (i.e. you changed lines then waited a bit and only after started sending data), then when to stop firing and finally another wait after which a change lines (so there was some “empty” at the start and at the end of a horizontal electron gun trace and you had to tune those so that the image didn’t start or end outside the screen).
There was also something similar for the vertical axis - i.e. instructing it to go back to the top and some empty lines at the top and the bottom.
I wouldn’t say it was convenient (it was a bloody text file with weird-looking numbers and you did run the risk of blowing up the CRT), but it was kinda fun that you could create your own crazy screen resolutions for X once you understood the principle of the thing.
I remember doing that configuration for X.
You had to tell it when to change lines, when to start firing on a new line (i.e. you changed lines then waited a bit and only after started sending data), then when to stop firing and finally another wait after which a change lines (so there was some “empty” at the start and at the end of a horizontal electron gun trace and you had to tune those so that the image didn’t start or end outside the screen).
There was also something similar for the vertical axis - i.e. instructing it to go back to the top and some empty lines at the top and the bottom.
I wouldn’t say it was convenient (it was a bloody text file with weird-looking numbers and you did run the risk of blowing up the CRT), but it was kinda fun that you could create your own crazy screen resolutions for X once you understood the principle of the thing.