I used to write graphics routines in the late 90s while at uni using TASM (Turbo Assembler). Good old INT13 on Intel x86. Inline ASM in Turbo Pascal was also handy. I implemented a Bresenham line algorithm from C and extracted ROM fonts for pretty graphics. I wrote a system that used INT1C to perform crude TDM multitasking in DOS. Not sure where i found that gem. I still have Peter Norton's book somewhere too. That low level disk access!