IBM 5170 Technical Reference page 419

housekeeping. Operations or routines that do not contribute
directly to the solution of the problem but do contribute directly
to the operation of the computer.
Hz. Hertz
image. A fully processed unit of operational data that is ready to
be transmitted to a remote unit; when loaded into control storage
in the remote unit, the image determines the operations of the
unit.
immediate instruction. An instruction that contains within itself an
operand for the operation specified, rather than an address of the
operand.
index register. A register whose contents may be used to modify
an operand address during the execution of computer instructions.
indicator.
(1)
A device that may be set into a prescribed state,
usually according to the result of a previous process or on the
occurrence of a specified condition in the equipment, and that
/"'""""\ usually gives a visual or other indication of the existence of the
prescribed state, and that may in some cases be used to determine
the selection among alternative processes; for example, an
overflow indicator. (2) An item of data that may be interrogated
to determine whether a particular condition has been satisfied in
the execution of a computer program; for example, a switch
indicator, an overflow indicator.
inhibited. (1) Pertaining to a state of a processing unit in which
certain types of interruptions are not allowed to occur.
(2)
Pertaining to the state in which a transmission control unit or an
audio response unit cannot accept incoming calls on a line.
initialize. To set counters, switches, addresses, or contents of
storage to 0 or other starting values at the beginning of, or at
prescribed points in, the operation of a computer routine.
input/output (I/O).
(1)
Pertaining to a device or to a channel that
may be involved in an input process, and, at a different time, in an
output process. In the English language, "input/output" may be
Glossary-17