PA-RISC Processors

PA-8700 (PCX-W2) processor

Overview

The PA-8700 processor is an 64-bit HP PA-RISC processor from HP, released in 2001 building on an enhanced PA-8500 core with several modifications. As with other PA-8x00 processors, the logic core is close to the original PA-8000 from 1997. The PA-8700 used significant larger on-chip L1 caches and TLB while switching to a new manufacturing process at IBM helped increase the clock speed to 750-875 MHz.

At its time of the early 2000s, the PA-8700 was one of the largest commercial processors shipping and one of the first manufactured in Silicon on Insulator (SoI). The PA-8700 is superscalar (4-way) and multi-processor (SMP) capable.

HP PA-8700 was followed by the dual-core PA-8800 processor, (almost) the end of the line for PA-RISC in 2004.

Details

PA-RISC version 2.0, 64-bit architecture, multi-processor capable, 4-way superscalar
Ten functional units: 2 integer ALUs, 2 shift/merge units, 2 complete load/store pipelines, 2 Floating Point multiply/accumulate units, 2 Floating Point divide/square root units
IRB: 56-entry instruction queue/reorder buffer
TLB: 240-entry fully-associative dual-ported
BTAC: 32-entry Branch Target Address Cache; BHT: 2048-entry Branch History Table
Cache 0.75 MB instruction and 1.5 MB data L1 on-chip, 4-way set associative, in independent 0.75 MB banks.
Memory up to 16 TB supported with 44-bit physical addresses
Memory and I/O controllers are external
Bi-endian support
MAX-2 multimedia extensions subword arithmetic for multimedia applications
Runway+ system bus, 125 MHz, 64-bit, DDR, about 2.0 GB/s peak bandwidth
Up to 750 MHz, 875 MHz on the PA-8700+ clock speed with 1.5 V core voltage
16.0×19.0 mm² die, 186,000,000 FETs, 0.18µ, 7-layer Silicon-on-Insulator CMOS packaged in a 544-pin LGA package

Used in

HP 9000 A400-6X (rp2430), A500-6X, A500-7X (rp2470), rp2405 servers
HP 9000 C3650, C3700, C3750 workstations
HP 9000 J6700 workstations
HP 9000 L1500-6X, L1500-7X, L1500-8X (rp5430), L3000-6X, L3000-7X, L3000-8X (rp5470) servers
HP 9000 N4000-6X, N4000-7X (rp7400) servers
HP 9000 N4000-6X, N4000-7X, N4000-8X (rp7405, rp7410) servers
HP 9000 Superdome mainframes (SD16000, SD32000, SD64000)

References

A 900 MHz 2.25 MByte Cache with On Chip CPU (PDF, 119 KB) J. Michael Hill and Jonathan Lachman (2000: ISSCC)
PA-RISC 2.0 Architecture (.pdf) Hewlett-Packard Company (1995)
HP taps new foundry for PA-RISC processors, EE Times, August 2001

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