IO.md

tags	cm12002 cs
links	[[Computer Systems Architectures]]
presentations	W09_L02_P01

IO

• Input/Output (IO) refers to any transfer of information between the CPU and external devices or systems, including peripheral devices, network devices, etc.

• External devices (or peripheral devices) provide a means of exchanging data between the computer's external environment and the computer itself.

  • They attach to the computer through a link to an IO module — a hardware component in a computer system that acts as an intermediary between the CPU and the peripheral devices
  • There are three categories of external devices:
    1. Human readable — used for communication with the computer user, e.g. monitors, printers, etc.
    2. Machine readable — used for communication with other equipment, e.g. disks, sensors, actuators, etc.
    3. Communication — used for communicating with remote devices such as a terminal, other machine readable devices, or another computer.

• The major functions for an IO module fall into the following categories:

  • Error Detection — detects and reports transmission errors.
  • Control and Timing — coordinates the flow of traffic between internal resources and external devices.
  • Processor Communication — involves command decoding, data, status reporting, address recognition.
  • Device Communication — involves commands, status information, and data.
  • Data Buffering — performs the needed buffering operation to balance device and memory speeds.

• There are three techniques for IO operations:

  1. [[Programmed IO]]
  2. Interrupt-driven IO
  3. Direct Memory Access (DMA)