NCR PC4I, Руководство пользователя

Страница: 147 / 167

GLOSSARY
HARDWARE
Physical equipment used in data processing. Contrast with
software.
HEAD
A device that reads, records, or erases data on a storage medium,
e.g., a small electromagnet used to read, write, or erase data on a
magnetic disk.
HEXADECIMAL DIGIT
A whole number in the hexadecimal numeral system (based on a
radix of 16). A hexadecimal digit can be expressed in any one of
sixteen different characters: 0,l,2,3,4,5,6,7,8,9,a,b,c,d,e,f.
HOUSEKEEPING
Computer operations that do not directly contribute toward the
desired results; in general, initialization, set-up, diagnostics.
I
ILLEGAL CHARACTER
A character or combination of bits which is not accepted as a
valid or known representation by the computer.
INDICATOR
A device which registers a condition in the computer.
INITIALIZE
To set counters, switches, and addresses to zero or other starting
values at the beginning of, or at prescribed points in, a computer
routine.
I/O
Abbreviation for “input and output”. Input is the data received by
the CPU from devices connected to it. Output is that which is sent
from the CPU to those devices.
INPUT
The introduction of data from an external storage medium into a
computer’s internal storage unit.
INSTRUCTION
A group of characters, bytes, or bits that defines an operation to
be performed by the computer.
OWNER S MANUAL G-9