User`s guide

CPMBX
Console Program Mailbox is used to pass information between operating
systems and the firmware.
CRC
Character code recognition. The use of pattern recognition techniques to
identify characters by automatic means.
CQBIC
CVAX to Q22–bus interface chip.
CSR
Control status register. A register used to control the operation of a device and
record the status of an operation or both.
CPU
Central processing unit. The main unit of a computer containing the circuits
that control the interpretation and execution of instructions. The CPU holds
the main storage, arithmetic unit, and special registers.
DCOK
Q22–bus signal indicating dc power is stable. This signal is tied to the Restart
switch on the System Control Panel.
DE
Diagnostic Executive is a component of the ROM-based diagnostics responsible
for set-up, execution, and clean-up of component diagnostic tests.
DMA
Direct memory access. A method of accessing a device’s memory without
interacting with the device’s CPU.
DNA
Digital Network Architecture.
EPROM
Erasable programmable read-only memory. EPROM is a type of read-only
memory that can be erased by using ultraviolet light, returning the device to a
blank state.
Glossary–2