IRQ9IRQ15

IRQ9IRQ15 refers to a range of Interrupt Request (IRQ) lines on older PC architectures, specifically IRQ9, IRQ10, IRQ11, IRQ12, IRQ13, IRQ14, and IRQ15. These are hardware signals used by devices to notify the CPU that they require attention or have data to transfer. In the original IBM PC architecture, IRQs were assigned to specific hardware components.

IRQ9 was often used for the display adapter, and in later systems, it was remapped to IRQ2 due to a cascading mechanism. IRQ10 and IRQ11 were typically assigned to various expansion cards and integrated peripherals. IRQ12 was commonly used for the PS/2 mouse, and IRQ13 was reserved for the floating-point unit (FPU) or math co-processor. IRQ14 and IRQ15 were generally designated for the primary and secondary IDE hard drive controllers, respectively.

As computer hardware evolved, the use and management of IRQs became more sophisticated with technologies like PCI and AGP, which allowed for dynamic IRQ sharing and assignment. However, understanding these legacy IRQ assignments is still relevant for troubleshooting older systems or when dealing with certain embedded or specialized hardware. Conflicts between devices attempting to use the same IRQ could lead to system instability or non-functional hardware.