The Amiga has a special mode called Extra Half Brite or EHB mode which doubles the maximum number of colors that can be displayed at one time. To use EHB mode, you must set up six bitplanes. Then set BPU =6 (bits 12, 13 and 14) in the BPLCON0 register. Set HOMOD =0 (bit 11) and DBLPF =0 (bit 10) in BPLCON0 . In this mode, the information in bitplane 6 controls an intensity reduction in the other 5 bitplanes. The color register output selected by the first five bitplanes is shifted to half-intensity by the sixth bitplane. This allows 64 colors to be displayed at one time instead of the usual 32. ECS playfield registers. ----------------------- For information concerning the playfield hardware and the Enhanced Chip Set, see Appendix C.
[Back to Amiga Developer Docs]