Compaq 21264, EV67 specifications Feprom, Fet, Feu, Fpga, Fpla

external cache

See second-level cache.

FEPROM

Flash-erasable programmable read-only memory. FEPROMs can be bank- or bulk- erased. Contrast with EEPROM.

FET

Field-effect transistor.

FEU

The unit within the 21264/EV67 microprocessor that performs floating-point calcula- tions.

firmware

Machine instructions stored in nonvolatile memory.

floating point

A number system in which the position of the radix point is indicated by the exponent part and another part represents the significant digits or fractional part.

flush

See cache flush.

forwarded clock

A single-ended differential signal that is aligned with its associated fields. The for- warded clock is sourced and aligned by the sender with a period that is two times the bit time. Forwarded clocks must be 50% duty cycle clocks whose rising and falling edges are aligned with the changing edge of the data.

FPGA

Field-programmable gate array.

FPLA

Field-programmable logic array.

FQ

Floating-point issue queue.

framing clock

The framing clock defines the start of a transmission either from the system to the 21264/EV67 or from the 21264/EV67 to the system. The framing clock is a power-of- 2 multiple of the 21264/EV67 GCLK frequency, and is usually the system clock. The framing clock and the input oscillator can have the same frequency. The add_frame_select IPR sets that ratio of bit times to framing clock. The frame clock could have a period that is four times the bit time with a add_frame_select of 2X. Transfers begin on the rising and falling edge of the frame clock. This is useful for sys- tems that have system clocks with a period too small to perform the synchronous reset

Alpha 21264/EV67 Hardware Reference Manual Glossary–7