Chapter 4 PA-RISC Computer Systems - OpenPA.net

PA-RISC Chipsets Pluto (zx1)
References
1. Astro External Reference Specification Introduction 84
Astro External Reference Specification Error Handling 85
Astro External Reference Specification R2I Operations 86
Astro External Reference Specification Register Map 87
Astro External Reference Specification Runway Interface 88
Astro External Reference Specification Memory Map 89
Hewlett-Packard Company (February 2000, Revision 1.2)
2.5.19 Pluto (zx1)
Many of the Itanium-based HP workstations and servers use the Pluto I/O and memory controller as
part of the zx1 chipset. Pluto is based on the Astro IOMMU, extending it for Itanium-2 processors and
bus interfaces, DDR memory and faster I/O links.
Pluto is a IOMMU and attaches to three different buses, acting as central crossbar:
1. Processor bus: Itanium-2 processor bus for one to four CPUs. The bus runs at maximum of
200 MHz with a width of 128-bits and has ECC-protection, for up to 6.4 GB/s data rate.
2. Two memory bus with a peak bandwidth of aggregated 8.0 GB/s at maximum clock of 266 MHz
DDR. Can be extended with the zx1 SME for more memory and higher peak datarate of 12.8 GB/s
3. I/O system based on eight separate 500 MB/s I/O links (ropes) which attach to individual PCI,
PCI-X or AGP bridges. Peak aggregate I/O bandwidth is 3.2 GB/s
Features
� Support for DDR SDRAMs
� Maximum supported memory of 16 GB (with 256 Mb DRAMs) or up to 64 GB with SME memory
extender
� Integrated I/O cache controller (IOCC)
� 16-entry I/O TLB
� 16-entry coherent I/O cache
� IOCC can serve as AGP GART
� Two rope quad controllers (RQCCs) that each control up to four I/O ropes and attach to the
IOCC
� Each RQCC can bundle the four I/O ropes into single, double or quad-wide bundles.
� Up to eight I/O ropes with a clock of up to 266 MHz (500 MB/s peak data rate), aggregate peak
would be 4,000 MB/s (which Pluto cannot sustain)
84 http://ftp.parisc-linux.org/docs/chips/astro_intro.pdf
85 http://ftp.parisc-linux.org/docs/chips/astro_errors.pdf
86 http://ftp.parisc-linux.org/docs/chips/astro_ioc.pdf
87 http://ftp.parisc-linux.org/docs/chips/astro_regmap.pdf
88 http://ftp.parisc-linux.org/docs/chips/astro_runway.pdf
89 http://ftp.parisc-linux.org/docs/chips/astro_sysmap.pdf
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