or from some ISA devices, EIRQ_REG can distinguish up to 8 ISA IRQs.
The Q40 custom chip is programmable to provide 2 periodic timers:
- - 50 or 200 Hz - level 2, !!THIS CANT BE DISABLED!!
+ - 50 or 200 Hz - level 2, !!THIS CAN'T BE DISABLED!!
- 10 or 20 KHz - level 4, used for dma-sound
Linux uses the 200 Hz interrupt for timer and beep by default.