PA-RISC information - since 1999

PA-RISC Chipsets

U2 and UTurn chipset

HP U2 and UTurn are PA-RISC chipsets used in HP 9000 workstations and servers. HP computers with 32-bit and 64-bit PA-RISC processors on Runway bus often used U2 and UTurn. U2 and UTurn are I/O adapters (IOA) and MMC/SMC their memory controllers that attach subsystems to the main Runway processor bus.

HP UTurn and U2 attach the GSC main system bus with devices and I/O via Runway bus to the CPUs. This setup allowed HP to use a standard frontend with UTurn in different PA-RISC system designs with different backends to support memory or I/O technologies.

U2 is the variant for 32-bit PA-7200 PA-RISC systems while later systems with 64-bit PA-8000 and PA-8200 processors use the UTurn follow-on.

A typical U2/UTurn system design and bus setup would look the following:

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MMC/SMC

Most systems with 64-bit PA-7200, PA-8000 or PA-8200 processors use a combination of HP MMC and SMC memory controllers to attach the main system memory to the Runway processor bus. I/O is controlled by the HP U2/UTurn I/O adapters on the same Runway bus.

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Dino/Cujo

HP Dino is the GSC to PCI bridge found in many older PCI PA-RISC workstations. This way, GSC and PCI buses did not need to be synchronized, simplifying the system design. Dino also implements a small set of I/O functions for the system. HP Cujo is a Dino bridge for 64-bit PCI.

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Documentation

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