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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…'
== 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)
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)
