overhead

1. Resources (in computing usually processing time or storage

space) consumed for purposes which are incidental to, but

necessary to, the main one. Overheads are usually

quantifiable "costs" of some kind.

Examples: The overheads in running a business include the cost

of heating the building. Keeping a program running all the

time eliminates the overhead of loading and initialising it

for each transaction. Turning a subroutine into inline

code eliminates the call and return time overhead for each

execution but introduces space overheads.

2. communications information, such as control, routing, and

error checking characters, that is transmitted along with the

user data. It also includes information such as network

status or operational instructions, network routing

information, and retransmissions of user data received in

error.

3. Overhead transparencies or "slides" (usually 8-1/2" x 11")

that are projected to an audience via an overhead (flatbed)

projector.

(1997-09-01)