Final answer:
The maskable interrupt is used by device controllers to request service from the CPU, allowing controlled management of interrupts by the CPU which can temporarily ignore these interrupts.
Step-by-step explanation:
The device controllers use the maskable interrupt to request service from the CPU. A maskable interrupt is one that can be turned off by the CPU when it is running a critical piece of code. This is different from a nonmaskable interrupt, which cannot be ignored by the CPU and must be dealt with immediately. Maskable interrupts for more controlled management of the processor's response to various types of service requests. The CPU can decide to ignore (or 'mask') these interrupts temporarily when processing them could lead to systems instability or when it is handling more important tasks.