To be more exact (in an excessive way), it uses the BIOS's code to set the video mode (INT 10h) which is probably a few dozen bytes (at least?) although I have been remiss at not ever reading them. And it depends on DOS configuring the memory space to leave an INT 20h call (to terminate the program) at a place that's easy to RET to. But, yeah, very little extra. But I'm not being negative at all and this is pretty nice code and on the impressive side of 256 byte demos from the 80s and 90s (and onward).
The VBIOS is around 32-64k. The modesetting path is probably a few k.
And it depends on DOS configuring the memory space to leave an INT 20h call (to terminate the program) at a place that's easy to RET to.
This has always been the case, and actually inherited from CP/M.
Also, MIDI - I'm not very familiar with demo programming, but I guess using MIDI saves a lot of bytes compared to trying to do something similar with only the PC speaker?
loading story #47688654
Yes, this is very minimal; if it were self-booting the INT 20h call wouldn't be needed, but there's no getting around the INT 10h, unless you specialize for very specific hardware.
The entire 5150 BIOS fit in 8k, so even if it were laden with BIOS calls (which it's not) then that would be an upper-bound.
Thanks :)
and yes, your observations are spot on.