Computer Organization & Architecture · topic
I/O interfaces, memory-mapped and isolated I/O, programmed I/O, the interrupt sequence, vectored and daisy-chain priority, masking and nesting, CPU overhead of polling and interrupts, and DMA: controller, bus handshake, burst, cycle-stealing and transparent modes with CPU-time fractions.
An I/O interface (device controller, I/O module) connects a peripheral to the system bus. It contains a few registers that the processor reads and writes: a data register, a status register (ready, busy, error) and a control register (commands, interrupt enable).
Direct memory access (DMA) lets an I/O interface move a block of data between a device and main memory without the processor handling each word.
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