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Interrupt Scheduler
The Interrupt Scheduler handles system timers and counters.
Interrupt Scheduler Routines
| Name | Description |
|---|---|
| ACTINT | Activate automatic interrupt service (timers, music, blackout) |
| CTIMER | Call custom timer |
| DECCTS | Decrement counters/timers under mask (used by ACTINT and DECCTS) |
| STIMER | Track and decrement game timers |
Interrupt Scheduler Routine Descriptions
ACTINT
ACTIVE INTERRUPTS
| Calling Sequence: | SYSTEM ACTINT or SYSSUK ACTINT |
| Arguments: | None |
| Outputs: | None |
| Function: | Sets IM=2, INLIN=200, sets I register + INFBK Calls TIMEX and TIMEY Enables interrupts |
| Description: | Once ACTINT is called, it provides interrupt service completely automatically. It runs the seconds timer, the game timer, the music processor, and blackout timers, plus CT0, CT1, CT2, CT3. Timers function every 1/60th of a second. |
CTIMER
CUSTOM TIMER
| Calling Sequence: | CALL CTIMER
|
| Input: | HL = address of custom time base B = value to load into time base 1 to 0 transition C = counter mask as in DECCTS |
| Notes: | None |
| Description: | HL is loaded and decremented. If HL != 0, then a return is executed, otherwise, HL is loaded with B and DECCTS is called. Registers HL, DE, BC, and AF are undefined upon exit. |
| Restrictions: | None |
