Software:demoscene:Monstra by Flash Production (1992)

1992 demoscene entry.

Demo description

(todo)

Recommended DOSBox-X configuration

[dosbox]
machine=vgaonly
memsize=2

[speaker]
pcspeaker=false

[sblaster]
sbtype=sbpro2
sbbase=220
irq=5
dma=1

[cpu]
core=normal
cycles=20000
cputype=pentium

You will be prompted for CPU & Speed, and music performance. The menus have a non-intuitive design: Make the selection and then hit ESCAPE to continue. You need to set pcspeaker=false because the demo turns it on for some reason. Each demo part will run until you hit ESCAPE.

VGA oddities

The ``Flash'' part of the demo, with copper bars and vertical bars, relies on the VGA hardware not buffering the Line Compare register to effectively repeat the same scanline down the screen as it does the other raster effects before allowing the Flash logo to appear at the bottom. If the VGA hardware does not act on the changed Line Compare register contents during raster, then the Flash logo stays at the top of the screen and none of the vertical bars are visible. The trick is similar to one of the VGA raster effects in the DOSLIB VGA test program, using the Line Compare register to make the VGA text repeat multiple times down the screen.

A capture of the effect on real hardware is available (here).

More information

More information (Pouet)