Compaq 21264 Hardware Reference Manual page 336

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 ana-
lyzes the error.
MAF
Miss address file.
main memory
The large memory, external to the microprocessor, used for holding most instruction
code and data. Usually built from cost-effective DRAM memory chips. May be used in
connection with the microprocessor's internal caches and an external cache.
masked write
A write cycle that only updates a subset of a nominal data block.
MBO
See must be one.
Mbox
This section of the processor unit performs address translation, interfaces to the
Dcache, and performs several other functions.
MBZ
See must be zero.
MESI protocol
A cache consistency protocol with full support for multiprocessing. The MESI protocol
consists of four states that define whether a block is modified (M), exclusive (E), shared
(S), or invalid (I).
MIPS
Millions of instructions per second.
miss
See cache miss.
module
A board on which logic devices (such as transistors, resistors, and memory chips) are
mounted and connected to perform a specific system function.
module-level cache
See second-level cache.
MOS
Metal-oxide semiconductor.
MOSFET
Metal-oxide semiconductor field-effect transistor.
Glossary
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Alpha 21264/EV67 Hardware Reference Manual