Difference between revisions of "External Interrupt"
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(Created page with '== External Interrupt (INT Pin) == The INT signal is internally used by the CPC (triggered at 300Hz, and divided by software to get 50Hz/60Hz Video interrupts). The BIOS does co…') |
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Revision as of 14:42, 18 June 2010
External Interrupt (INT Pin)
The INT signal is internally used by the CPC (triggered at 300Hz, and divided by software to get 50Hz/60Hz Video interrupts). The BIOS does contain some provisions for sharing the INT signal with external interrupts. However, most peripherals are using NMI's, which don't require to recurse conflicts with internal INTs.
Peripherals that do use external INTs:
- Music Machine - accordingly to the manual: It can "disable" the internal interrupt, and replace it by external MIDI/ACIA interrupt. Unknown if/how it is really doing that, "disabling" the internal interrupt could be probably done only "shortcutting" the INT signal to 5V, which would be a rather aggressive solution - so maybe the manual only meant that software "ignores" the internal interrupt (?) - also, it referred to IRQ, which could eventually also mean NMI rather than INT...? - the Music Machine software isn't in the internet yet, so one can't disassemble/verify this.
See also
- NMI - Non-maskable Interrupts (more commonly used by peripherals)
