Bit Plane Control Register (new control bits)
| Bit | Function | Description |
|---|---|---|
| 15 | X | [Not in reference manual] don`t care- but drive to 0 for upward compatibility |
| 14 | X ZDBPSEL2 | [Not in reference manual] 3 bit field which selects which bitplane is to be used for ZD when ZDBBPEN is set- 000 selects BB1 and 111 selects BP8. |
| 13 | X ZDBPSEL1 | [Not in reference manual] |
| 12 | X ZDBPSEL0 | [Not in reference manual] |
| 11 | X ZDBPEN | [Not in reference manual] Causes ZD pin to mirror bitplane selected by ZDBPSELx bits. This does not disable the ZD mode defined by ZDCTEN, but rather is "ored" with it. |
| 10 | X ZDCTEN | [Not in reference manual] Causes ZD pin to mirror bit #15 of the active entry in high color table. When ZDCTEN is reset ZD reverts to mirroring color (0). |
| 09 | X KILLEHB | [Not in reference manual] Disables extra halfbrite mode. |
| 08 | X RDRAM=0 | [Not in reference manual] Causes color table address to read the color table instead of writing to it. |
| 07 | X SOGEN=0 | [Not in reference manual] When set causes SOG output pin to go high |
| 06 | PF2PRI | Gives playfield 2 priority over playfield 1. |
| 05 | PF2P2 | Playfield 2 priority code (with resp. to sprites). |
| 04 | PF2P1 | |
| 03 | PF2P0 | |
| 02 | PF1P2 | Playfield 1 priority code (with resp. to sprites). |
| 01 | PF1P1 | |
| 00 | PF1P0 |