The Neo Geo has incredibly powerful sprite based hardware, but can it do raster effects?
Raster effects are where changes to the graphics hardware registers are made mid frame, usually timed to be in the horizontal blanking period between scanlines but not always.
The palette information gives a hint:
The maximum number of colors on screen without timer interrupt tricks is: 256 palettes * 15 colors = 3840 (out of 2^16 = 65536).
So, yes, it seems possible thanks to the timer interrupt
The value of this counter is decremented by the pixel clock, which runs at 6MHz (166.7ns period).
With this resolution of 1 pixel, it looks like it's designed for raster/scanline effects.
Examples of usage mention sophisticated effects like sprite deformation. One famous example is Neo Turf Master, where timer interrupts were used to fake 3D effects
