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I/O Devices

Input/Output (I/O) devices
  • allow programs to communicate with "the outside" world
  • have significantly different characteristics to memory-based data
  • varying in their characteristics   (storeable?, capacity, speed, chunk size)
Memory-based data
  • fast (ns) random access via (virtual) address
  • transfer data in units of bytes, halfwords, words
Device data
  • much slower (ms) access, random or sequential
  • some (eg disk drives) transfer data in blocks (e.g. 128B, 512B, 4KB, ...)