Intel 8259 interrupt controller: 

The 8088 processor has only two interrupt control inputs, and interrupt request (INTR) and non mask able interrupt (NMI). NMI are interrupts that can't be masked (for examples: power loss ,memory parity error). The interrupt controller has many functions:

• It's receives interrupt requests from up to eight different sources.
• It's prioritized and queues interrupts that come at the same time
• it 's masks interrupt requests when instructed by the CPU
• It's processes the CPU's interrupt-acknowledge signal by sending the interrupt vector number to the CPU.