| Bits | Description |
|---|---|
| 7 | Unlock port 0x7ffd (read 1 indicates port 0x7ffd is not locked) |
| 6 | Disable ram and port contention (soft reset = 0) |
| 5 | AY stereo mode (0 = ABC, 1 = ACB) (hard reset = 0) |
| 4 | Enable internal speaker (hard reset = 1) |
| 3 | Enable 8-bit DACs (A,B,C,D) (hard reset = 0) |
| 2 | Enable port 0xff Timex video mode read (hides floating bus on 0xff) (hard reset = 0) |
| 1 | Enable turbosound (currently selected AY is frozen when disabled) (hard reset = 0) |
| 0 | Implement issue 2 keyboard (hard reset = 0) |