T he AD SP-2104/AD SP-2109 uses a vectored interrupt scheme: when an interrupt is acknowledged, the processor shifts program control to the interrupt vector address corresponding to the interrupt received. Interrupts can be optionally nested so that a higher priority interrupt can preempt the currently executing interrupt service routine. Each interrupt vector location is four instructions in length so that simple service routines can be coded entirely in this space. Longer service routines require an additional JUMP or CALL instruction.
SK85C on stock| DO | D1 | D2 | D3 | D4 | D5 | D6 | D7 | D8 | D9 | D10 | D11 | D12 | D13 | D14 | D15 |
| | | L | | Mode Set | Pro Logic Mode | Center Mode | Auto- BalanCE | Noise Sequencer | | |
| L | L | H | | L | Delay l lme | Space Surround Mode | L | H |
| | | L | L | Delay Volume | Cch Volume |
| L | H | Feedback Volume | SLch Volume | cr | ip |
| L | H | H | L | | SRch Volume | Addi | 'ess |
| H | H | | sw- VOL Set | SWch Volume |
| | | L | | Cch Trimmer | SWch Trimmer |
| H | L | H | | SLch Trimmer | SRch Trimmer |
| H | H | Test Mode (user inhibit) |
| | | | | | | | | | | | | | | |
