chernandezba wrote:1. what are the display formats for modes 16c and 256c?
256c.
Bits 7..0 are index to CRAM.
Each line address is aligned to 512.
GXOffs and GYOffs add offset to X and Y start address in pixels.
16c.
Bits are index to CRAM, where PalSel.GPAL is 4 MSBs and the pixel are 4 LSBs of the index.
Pixels are bits7..4 - left, bits3..0 - right.
Each line address is aligned to 256.
GXOffs and GYOffs add offset to X and Y start address in pixels.
chernandezba wrote:2. Can I have normal ZX video mode but with other resolutions, like 320x200? What format would be in this case?
No you can't because ZX screen addressing makes this idea senseless in either way.
You can select any frame size when ZX mode is on without harming any animals, but you'll see just messed up screen.