Communicating with machines
is slow (compared to internal operations) because ...
it may involve mechanical
parts (e.g., disks, tape drives).
it may involve shared,
inexpensive (slow) resources (e.g., local area networks, phone lines, modems).
Communicating with humans
is very slow for obvious reasons.
are separate, special purpose computers that handle the details of I-O for a particular
device; they can receive data and instructions from the CPU, carry out
operations independently (in parallel), and report back, allowing the CPU
to do lots of other useful work in the meantime.
- Storage devices are devices that are capable of both input and output. While such devices are in one package they generally have totally separate internal input and output systems.
Last Updated 2001/09/14
L.Heath, 2000 with upgrades by J.A.N. Lee