not overshoot.
I have built "video cards" from before "PC" was a word. I made "CRT terminals" also known as dumb terminals. Designed CRT monitors and TVs for many companies. Done vector displays for radar. Designed video boards for computers.
This is a timing error. At the end of a character the software goes off and leaves the last dot on, with out moving the dot to the next location. (When I say leaves the last the last dot on I mean; If the dot is on it leaves it on. If the last dot is off if leaves it off)
I have thought about this. It does not matter if the scan is Left to right or right to left or top to bottom or bottom to top. There is good evidence the scan is L to R.
Note the vertical part of the L does not have "over shoot". The last dot of the L is too bright.
Line 1 shows what happens when the dot is left on for 2 dots of time.
Line 2 shows a bright spot because the dot is on for 4X6=24 clocks.
Line 3 is very bright because the dot is on for the length of the orange line.
Line 4 is also a long line.
Line 6 and the L below it are examples if a long amount of time.
Now compare to Line 7 which is shorter.
View attachment 91943
If this is a simple video amp over shoot then all single dots should be too bright. If you look at the horizontal line of the L it is made up of 5 dots not a single line. The designer chose to make the video 50% on 50% off for a single dot. This way the frequency response of the video amp (Z amp) is not an issue. One dot, two dots......5 dots all have the same frequencies.