Input/output
Interface
An I/O interface serves as a crucial communication link between a CPU and external devices through a bus. It plays a vital role in interpreting device addresses, executing handshaking commands like BUSY and READY, and facilitating data format conversion between serial and parallel forms. Interrupts are generated by the interface to signal the processor for further processing. Additionally, memory-mapped I/O enables hardware interaction through specific memory locations using assembly language instructions.
Higher-level Implementation
Operating systems abstract files and devices into streams for handling input and output operations. Programming languages like C and C++ treat files and devices as streams for manipulation. In ALGOL 68, input and output are collectively referred to as transput. The concept of I/O monad allows programs to describe I/O actions without causing side-effects, while the C standard library offers functions for stream manipulation.
Channel I/O
Channel I/O involves specific instructions dedicated to I/O operations, addressing channels or both channels and devices. Channels asynchronously manage addressing and control information, providing greater flexibility compared to DMA for I/O tasks.