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29 September 1997 – Subject To Change
Glossary
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direct memory access (DMA)
Access to memory by an I/O device that does not require processor intervention.
dirty
One status item for a cache block. The cache block is valid and has been written so
that it may differ from the copy in system main memory.
dirty victim
Used in reference to a cache block in the cache of a system bus node. The cache
block is valid but is about to be replaced due to a cache block resource conflict. The
data must therefore be written to memory.
DRAM
Dynamic random-access memory. Read/write memory that must be refreshed (read
from or written to) periodically to maintain the storage of information.
DTL
Diode-transistor logic.
dual issue
Two instructions are issued, in parallel, during the same microprocessor cycle. The
instructions use different resources and so do not conflict.
ECC
Error correction code. Code and algorithms used by logic to facilitate error detection
and correction. See also ECC error.
ECC error
An error detected by ECC logic, to indicate that data (or the protected “entity” has
been corrupted. The error may be correctable (soft error) or uncorrectable (hard
error).
ECL
Emitter-coupled logic.
EEPROM
Electrically erasable programmable read-only memory. A memory device that can
be byte-erased, written to, and read from. Contrast with FEPROM.