Noun
IRQ (plural IRQs)
(computing) Initialism of interrupt request.
Instead of stacking the PC and CC registers (normal 6809 behavior) the FIRQ interrupt can be set to stack the entire register set, as the IRQ interrupt does. Source: Internet
However, ISA motherboards include pull-up resistors on the IRQ lines, so well-behaved devices share ISA interrupts just fine. Source: Internet
It exists only on the stack, where BRK and PHP always write a 1, while IRQ and NMI always write a 0. The "SO" input pin, when asserted, will set the processor's overflow status bit (deasserting it does not clear the overflow bit, however). Source: Internet
However, if the IRQ line remains asserted after the servicing of the NMI, the processor will immediately respond to IRQ, as IRQ is level sensitive. Source: Internet
It is therefore possible to connect up to 6 devices that use one 8-bit IRQ each, or up to 5 devices that use one 16-bit IRQ each. Source: Internet
On the motherboard are also the ROM subsystem, DMA and IRQ controllers, coprocessor socket, sound (PC speaker, tone generation) circuitry, and keyboard interface. Source: Internet