Gregory's Serverremember that Thinkpad 700 from earlier? i started a massive project to build a replacement solid state hard drive for it. the drives were not IDE; they were a special IBM interface called DBA-ESDI. https://mastodon.social/@tubetime/110783604330499249
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 at the last Electronics Flea Market (in September) i found a strange bit of electromechanical aircraft avionics. check it out! https://mastodon.social/@tubetime/111043677193721723 some old DOS utilities had a graphical mouse cursor in text mode! i’ve investigated how they did it. https://mastodon.social/@tubetime/111123817309591559 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 most recently, i reverse engineered a rare Apple II sound card (a sampler) using some blurry photos AND ARTWORK ON A RECORD ALBUM COVER!! https://mastodon.social/@tubetime/111508413193886509 and we’re all caught up! i’ve got a bunch of projects planned for next year. thanks for coming along with me. best wishes to you all for a happy 2024! @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 have you seen Impulse Tracker? It does a lot of neat things with dynamic text mode fonts like a simple oscilloscope for the sounds @tubetime that was the next step after spark gap transmitters, IIRC. @tubetime A friendly Swedish radio engineer told me of his visit to SAQ (the transmitter pictured?) some time in early 2000. I have too much noise to pick up any transmissions at home though. |
did you know that some early radio transmitters were electromechanical? i didn’t either! https://mastodon.social/@tubetime/110970146022678448