GRP2 and GRP3 mystery
randoCreated:
Any graphics page can be used for any purpose.
By default:
GRP0: upper screen graphics
GRP1: lower screen graphics
GRP2: none
GRP3: none
GRP4: upper screen sprites, lower screen sprites
GRP5: upper screen BG tiles, lower screen BG tiles
But you can use GPAGE, SPPAGE, and BGPAGE to change these.
Like when I did GPAGE 2,2 after using sb sprite tool, I got the top screen with the grid.Because you can use any graphic page for drawing and displaying images. SBGED is programmed to use pages 2 and 3 for its interface because they wanted to make the images on 0 and 1 editable (since those pages are more likely to be used.)