Digital Equipment 300 Series AXP Reference Manual page 286

halt
The action of stopping the CPU from processing. This action
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.
hard error
A nonrecoverable error.
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 form is equal to 9 in hexadecimal form.
hexword
A length of 256 bits, 16 words, 8 longwords, or 32 bytes.
icon
A graphical symbol appearing on the system that identifies
drives, ports, switches, and indicators.
initialization
The sequence of steps that prepare the system to start.
Initialization occurs automatically after a system has been
turned on.
I-cache
Instruction cache. A high-speed memory reserved for the storage
of instructions. Contrast with D-cache.
input/output (I/O) device
A piece of equipment that transmits data to (input) and from
(output) the system. For example, a terminal or a mouse. See
mouse.
Glossary–14