IBM XT 5160 Technical Reference page 396

open collector. A switching transistor without an internal
connection between its collector and the voltage supply. A
connection from the collector to the voltage supply is made
through an external (pull-up) resistor.
operand. ( 1) An entity to which an operation is applied.
(2) That which is operated upon. An operand is usually identified
by an address part of an instruction.
operating system. Software that controls the execution of
programs; an operating system may provide services such as
resource allocation, scheduling, input/output control, and data
management.
OR. A logic operator having the property that if P is a
statement, Q is a statement, R is a statement,... , then the OR of P,
Q,
R, .. .is true if at least one statement is true, false if all
statements are false.
OR gate. A gate in which the output is 1 only if at least one
input is 1.
output. Pertaining to a device, process, or channel involved in an
output process, or to the data or states involved in an output
process.
output process. (1) The process that consists of the delivery of
data from a data processing system, or from any part of it.
(2) The return of information from a data processing system to
an end user, including the translation of data from a machine
language to a language that the end user can understand.
overcurrent. A current of higher than specified strength.
overflow indicator. (1) An indicator that signifies when the last
line on a page has been printed or passed. (2) An indicator that
is set on if the result of an arithmetic operation exceeds the
capacity of the accumulator.
overrun. Loss Of data because a receiving device is unable to
accept data at the rate it is transmitted.
overvoltage. A voltage of higher than specified value.
Glossary-25