User:Henriok/PowerPC 970

The PowerPC 970, PowerPC 970FX, PowerPC 970GX, and PowerPC 970MP, are 64-bit Power Architecture processors from IBM introduced in 2002.

The 970 family was created through a collaboration between IBM and Apple. The project went under the codename GP-UL or Giga Processor Ultra Light, where Giga Processor was the codename for the POWER4 from which the core was derived. When Apple introduced the Power Mac G5 they stated that this was a five year collaborative effort, with multiple future generations, but it didn't last that long. Apple had to retract the promise to deliver a 3 GHz processor one year after its introduction and IBM could never get the power consumption down far enough for these processors to fit into a portable computer. Apple only used three variants of the processor.

IBM offers its JS20/JS21 blade modules and some low-end workstations and System p servers are based on PowerPC 970. It it also used in some high end embedded systems like Mercurys Momentum XSA-200. IBM is also licensing the PowerPC 970 core for use in custom applications. A common misconception is that the PowerPC 970 was the core in IBM's Xenon processor in Microsoft's Xbox 360, but this is false. That processor is using cores similar to the Power Processing Element (PPE) in the Cell microprocessor.

Design
The PowerPC 970 is a single core, stripped down version of the POWER4 and can process both 32-bit and 64-bit PowerPC instructions natively. It has a hardware prefetch unit and a three way branch prediction unit which can track over 200 instructions simultaneously, issuing up to five instructions per cycle to either of eight processing units (two integer, two double precision floating point, two load/store units and two AltiVec SIMD units). The processor has a bi-directional 64-bit front side bus to the system controller chip (northbridge) running at up to half the processor core speed.

Problems

 * The PowerPC 970 consumed more power than older PowerPC chips, meaning it could not be fitted into Apple's PowerBook or iBook that were using the PowerPC G4. As a result, Apple's laptops continued to be fitted with the older G4 chip until the Apple-Intel transition.
 * All PowerPC 970 models lack the instruction to do little/big endian swapping. This proved to be a problem for Microsoft Virtual PC, which relied on this feature in G3 and G4 processors to accelerate performance.
 * The PowerPC 970 lacks certain features that the POWER5 processors have, such as virtualization, and microcode necessary to run i5/OS; as a result, IBM cannot make PowerPC 970-equipped blade modules for its System i server line.

PowerPC 970
The PowerPC 970 was announced by IBM in October 2002. It was released in Apple Computer's Power Mac G5 in June 2003 (in keeping with its previous naming conventions, Apple termed the PowerPC 970 based products G5, for the fifth generation of PowerPC microprocessors). IBM released its first PowerPC 970 blade servers, the BladeCenter JS20, in November 2003.

The PowerPC 970 had 512 KiB of full-speed L2 cache and clock speeds from 1.6 to 2.0 GHz. The front side bus ran at half the processor's clock speed.

PowerPC 970FX
The PowerPC 970FX used a 90 nm manufacturing process and has a maximum power rating of 11 watts at 149 degrees Fahrenheit while clocked a 1Ghz and a maximum of 48 watts at 2Ghz.

Apple released their 970FX-powered machines throughout 2004: the Xserve G5 in January, the Power Mac G5 in June, and the iMac G5 in August. The Power Mac introduced a top clock speed of 2.5 GHz while liquid-cooled (eventually reaching as high as 2.7 GHz in April 2005). The iMac ran the front side bus at a third of the clock speed.

PowerPC 970MP
IBM released the PowerPC 970MP, code-named "Antares", in the 3rd quarter of 2005. The 970MP is a dual-core processor with clock speeds between 1.4 and 2.5 GHz, and a maximum power usage of 37 watts at 1.7Ghz and 100 watts at 2.5Ghz. Each core has 1 MiB of L2 cache, twice that of the 970FX. Like the 970FX, this chip was produced at the 90 nm process. When one of the cores is idle, it will enter a "doze" state and shut down. The 970MP also includes partitioning and virtualization features. 

The PowerPC 970MP replaced the PowerPC 970FX in Apple's high-end Power Mac G5 computers, while the iMac G5 and the legacy PCI-X Power Mac G5 continued to use the PowerPC 970FX processor. The PowerPC 970MP is used in IBM's JS21 blade modules.

PowerPC 970GX
The single core version of PowerPC 970MP, the PowerPC 970GX, was introdueced in October 2006 but supposedly canceled in early 2007. The PowerPC 970MP and 970GX share characteristics such as 1 MiB L2 cache and speeds from 1.2 to 3 GHz and power usage ranges from 16 W at 1.6 GHz to 85 W at 3 GHz. These were also manufactured using the same 90 nm fabrication process. 

Northbridges
There are three dedicated northbridges for PowerPC 970-based computers, all manufactured by IBM:


 * CPC925—Apple designed it and called it U3 or U3H (with ECC). Manufactured on a 130 nm process. Dual 550 MHz bi-directional processor buses, 400 MHz DDR-controller, x8 AGP and 400 MHz 16-bit HyperTransport-tunnel. Capable of managing up to 2 processors (2x 970/970FX).
 * CPC945—Designed by IBM and called U4 by Apple. Manufactured on a 90 nm process. Dual 625 MHz bi-directional processor buses (1-4 processor cores), 533 MHz DDR2-controllers (up to 64 GB ECC RAM), x16 PCIe, and 800 MHz 16-bit HyperTransport-tunnel. Capable of handling up to 4 processors (2x 970MP).
 * CPC965—Was to be released in 2007 but was supposedly canceled. Is was a single-processor bridge. Featured a 533 MHz DDR2 controller (up to 8 GB ECC RAM), x8 PCIe, 4x Gbit Ethernet, USB2, Flash-interface, IPv4 TCP/UDP offloading, integrated PowerPC 405 processor for management and configuration.