Yeah, I remember getting a huge Microsoft reference book as a birthday present that listed all the BIOS, DOS and VGA system calls and their INT numbers and argu

Yeah, I remember getting a huge Microsoft reference book as a birthday present that listed all the BIOS, DOS and VGA system calls and their INT numbers and arguments. I then used it and DEBUG to write a tiny 'paint' program in ~80 bytes that did the following: 1. entered VGA mode 2. enabled the mouse cursor 3. checked the mouse status 4. turned on the pixel at the mouse location if the button was down 5. goto 3