half-height disk
Any 1 5/8-inch (4.1-centimeter) high, fixed drive that is 3½ inches
(9-centimeters) wide, such as those in the RZ family; or a 1
5/8-inch high removable drive that is 5-inches (12.7-centimeters)
wide, such as a compact disc.
halt
The action of stopping the CPU from processing, which involves
console mode and brings the system under the control of the
console program. A halt can occur when an internal system error
is detected, when you enter the HALT command at the console
terminal, or when you press the Halt button on the back of the
system unit.
hardware
The physical equipment—mechanical and electrical—that makes
up a system. Compare with software.
hexadecimal
A numbering system using the base 16 that is a shorthand
method for representing binary numbers. Using this method,
each four bits is converted into a single hexadecimal digit. For
example, 1001 in binary is equal to 9 in hexadecimal.
hit
A signal sent from the cache control logic to the CPU to indicate
that a valid copy of a desired memory location is currently in
cache.
icon
A graphical symbol on the system unit that identifies drives,
ports, switches, and indicators.
IEEE
Abbreviation for Institute of Electrical and Electronics
Engineers.
initialization
The sequence of steps that prepare the system to start.
Initialization occurs automatically after a system has been
turned on.
Glossary–16
