The register that stores all interrupt requests is :

Answer: Interrupt request register

Explanation: The Interrupt Request Register records pending interrupt requests until the processor acknowledges and services them. Each bit typically corresponds to an interrupt line that is awaiting handling.

• Interrupt Request Register: stores pending interrupt requests; this is the register referenced by the question.

• Interrupt Mask Register: used to mask (disable) or unmask specific interrupts; it does not record requests.

• Interrupt Service Register: indicates which interrupt is currently being serviced by the processor, not which are pending.

• Status Register: holds general status flags (for example zero, carry, interrupt-enable) and is not the register that stores interrupt requests.