Compaq EV68A specifications Pqfp, Prom, Ram, Ras, Raw, Readblock

Models: EV68A

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PQFP

Plastic quad flat pack.

primary cache

The cache that is the fastest and closest to the processor. The first-level caches, located on the CPU chip, composed of the Dcache and Icache.

program counter

That portion of the CPU that contains the virtual address of the next instruction to be executed. Most current CPUs implement the program counter (PC) as a register. This register may be visible to the programmer through the instruction set.

PROM

Programmable read-only memory.

pull-down resistor

A resistor placed between a signal line and a negative voltage.

pull-up resistor

A resistor placed between a signal line to a positive voltage.

QNaN

Quiet Nan. See NaN.

quad issue

Four instructions are issued, in parallel, during the same microprocessor cycle. The instructions use different resources and so do not conflict.

quadword

Eight contiguous bytes starting on an arbitrary byte boundary. The bits are numbered from right to left, 0 through 63.

RAM

Random-access memory.

RAS

Row address select.

RAW

Read-after-write.

READ_BLOCK

A transaction where the 21264/EV68A requests that an external logic unit fetch read data.

read data wrapping

System feature that reduces apparent memory latency by allowing read data cycles to differ the usual low-to-high sequence. Requires cooperation between the 21264/EV68A and external hardware.

21264/EV68A Hardware Reference Manual

Page 339
Image 339
Compaq EV68A specifications Pqfp, Prom, Ram, Ras, Raw, Readblock