all QBASIC tutorials:

"your scrollers need something to scroll from, so always hold a screen mirror in an array, draw to that and blit it to the screen"

but like

i can scroll anything on screen in Mode 13 with PEEK/POKE. In like... 7 lines? Probably 5 if I fuck with it some?

it's even fast enough to only take 3 frames to scroll one pixel on a 2GHz vCPU!

Qbasic is still a thing? 😂

@Kimmax it is when i get ahold of it goddammit

demo and die

My first programming language *sniff*

The reason you work with a shadow frame buffer is that it is switched to the actual screen right when the monitor syncs vertically. Makes only sense for CRT, but these were common back then.

If you fuck around with the active screen buffer right away, then depending on where the CRT ray is in relation to your poking, you may get an odd mix between the new picture and the old one so that moving things would seem to stutter.

You could also dig up Turbo C++ for DOS. It has really good help files built in.

@Fast-Nop not a shadow buffer in raw RAM, a DATA array.

The slowest shit in the world.

That's what these people use.

The PEEK/POKE method is around 4x faster, and MS-DOS only updates the screen data every frame even after I write to it ahead of the beam, so even on a CRT it looks okay.