OpenPA.net

PA-RISC Chipsets

PA-RISC on zx1

The zx1 chipset was designed for HP Itanium-based systems but used in some of the later PA-RISC based servers as well. It consists of two purpose-built main parts that connect the processor, memory and I/O to the Itanium system main buses: The last PA-RISC systems (PA-8800/PA-8900) and several second-generation Itanium systems use the HP zx1 chipset, conceptually similar to Astro systems but with higher datarates and options, based on Itanium 2/McKinley buses.

System bus design

The rest of the I/O chipset is made up of standard third-party I/O parts, such as SCSI controllers, Ethernet devices etc.

↑ up

Pluto

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.

Bus attachments

Memory

Other features

Used in

References

  1. zx1 mio (Memory and I/O) External Reference Specification Hewlett-Packard Company (March 2003, Revision 1.0)

↑ up

Mercury

Mercury is a PCI/AGP bridge for systems based on I/O ropes. It is part of the zx1 chipset used on Itanium systems (called zx1 I/O adapter), and based on the Elroy PCI bridge, extending it for AGP devices and faster I/O ropes. Most systems use several Mercury chips to attach PCI/AGP buses to the multiple I/O ropes. Each Mercury attaches one PCI or AGP bus to up to four 500 MB/s I/O ropes.

Mercury is most often used together with the Pluto I/O and memory controller of the zx1 chipset.

Bus attachments

Other features

Used in

References

  1. HP zx1 ioa ERS External Reference Specification Ropes to AGP/PCI/PCI-X Bridge (.pdf) Hewlett-Packard Company (April 2003, Revision 3.2)

↑ up