in October, i spent a bunch of time reverse engineering the power board from the IBM Thinkpad 700. it was a good excuse to switch to KiCAD 7, which allows you to overlay your layout on top of an image–perfect for reverse engineering work! https://mastodon.social/@tubetime/111298635503517686

@tubetime It was done dynamically redefining the appearance of a group of characters. This was only possible on VGA (and some older EGA) video cards.

Assuming the mouse pointer can move one pixel in any direction, and the mouse pointer occupies the room of only one character, you will need to redefine one, two, or four characters, depending on the pointer location.

@tubetime oh! redefinable fonts! lovely feature of the EGA and VGA cards!

@tubetime Oh, that was not that difficult. VGA could display two 256 char fonts at once. You selected thag by a single bit in the color attribute. All you need to do is to render the characters occupied by the mouse-cursor into font2 and put the mouse-cursor image on top of it. Then adjust character and attributes as needed.

You could render quite a bit of bitmap graphics that way in text-mode.

@tubetime @root42 Huh?! I only saw the ones that had a ♦︎ character in reversed colors that moved when you moved the mouse device. An actual inverted arrow image is impressive!

@tubetime have you seen Impulse Tracker? It does a lot of neat things with dynamic text mode fonts like a simple oscilloscope for the sounds