Instruction manual

Machine check
An operating system action triggered by certain system hardware-detected errors
that can be fatal to system operation. Once triggered, machine-check handler
software analyzes the error.
Masked write
A write cycle that updates only a subset of a data block
Main configuration table
A data structure containing a list of the devices in the system and a pointer to
the device configuration table corresponding to each device. Loaded by system
ROM at initialization.
MCT
See main configuration table.
MIPS
Millions of intructions per second.
Miss
Indicates that a copy of a memory location is not in cache.
Naturally-aligned data
Data stored in memory such that the address of the data is evenly divisible by
the size of the data in bytes. For example, an aligned longword is stored so that
the address of the longword is evenly divisible by 4.
NVRAM
Nonvolatile random-access memory. Memory that retains its information in the
absence of power, such as magnetic tape, drum, or core memory.
PALcode
Alpha AXP privileged architecture library code, written to support Alpha
processors. PALcode implements architecturally defined behavior.
Parity
A method for checking the accuracy of data by calculating the sum of the number
of ones in a piece of binary data. Even parity requires the correct sum to be an
even number. Odd parity requires the correct sum to be an odd number.
PBS bits
A three-bit field in the I/O Slot configuration register (IOSLOT) corresponding to
one slot; the ‘‘P’’ bit is the configuration bit for parity enable; the ‘‘B’’ bit specifies
whether the option supports block-mode write operations; the ‘‘S’’ bit specifies
whether virtual DMA is enabled.
PROM
Programmable read-only memory.
RAMDAC
Random-access memory digital/analog converter.
Glossary–3