when trying (unsuccessfully) to get the nvidia driver working correctly for my card, i wondered if a few registers weren't slightly off. i could be wrong and this was a long time ago, but fwiw:
vga->crt[0x04] = mode->shs/8 - 1; /* differs by
-1 */
vga->crt[0x13] = (vga->virtx/8)*(mode->z/8);
vga->crt[0x15] = mode->vt - 1; /* differs by -1 */
the 0x13 register was a particular problem. with the normal setting,
the cursor just froze up and wouldn't move.
- erik
