Archive for January, 2011

January 24th, 2011 ~ by admin

IBM’s Server Processors: The RS64 and the POWER

IBM POWER1 Data Cache circa 1990 - 30MHz

IBM in the late 1990s was making a wide variety of processors, from the Cyrix Design 6x86MX, to fab work for AMD on the K6, to the PowerPC line used in Apple computers.  Most of these processors were low margin designs for the consumer market.  What IBM is best known for, and best at, is server and workstation processors.  The kind of processors you will find by the thousands in Top 500 Supercomputers.

There were three distinct architectures IBM used in this market.  The POWER (Performance Optimization With Enhanced RISC) processor originated in 1990 as a new deign for IBM.  IBM also was working on with Apple and Motorola in a consortium known as AIM to design a PC based processor architecture, loosely based, or inspired by, POWER.  This became known as the PowerPC.  IBM also was looking for a solution to replacing their old AS/400 CISC based computers.  A processor architecture to smooth the transition from CISC, to full on RISC was needed. A subset of the PowerPC design was developed with added instructions from the POWER2 and AS/400 called PowerPC-AS.  The first CPU to use this architecture was the A10, released in 1995 at 77MHz

IBM RS64 IV 600MHz Dual Core - 2001

The RS64 line implemented the PowerPC-AS architecture and was initially released in 1997.  RS64 designs were focused mainly on transaction processing and other integer intensive applications.  Their floating point performance was not as good as the POWER architecture.  Debuting at 125MHz with 128kb of L1 cache, and 4MB of off chip L2 cache.  By 2000 IBM had continually improved upon the RS64 architecture, as well as fab processes.  The RS64-IV, the final RS64 processor, was released at 600MHz and topped out at 750MHz.  At the time the POWER line (now at the POWER3) has stagnated, the RS was able to clock twice as fast, and at less power (15W per core)

POWER3-II 375MHz - 2000

In 1998 IBM released the POWER3, the third generation in the POWER line, and the contemporary to the RS64-IV.  The POWER3 essentially merged the full 64-bit PowerPC instruction set into the POWER line.  Initially it ran at 200MHz with 96kb of L1 cache, 16MB of off chip L2 cache. It was manufactured on a hybrid 0.35/0.25u process. In 2000 IBM released the POWER3-II, a process shrink to 0.22u, with other enhancements, that brought the POWER line up to 450MHz.  Still the POWER3 languished in pure speed (at least in integer) against the RS64-IV.

Having two independent processor lines is extremely expensive to maintain.  Support costs, software costs, R&D, etc all were double what they would be with a single unified architecture.  In 2001 IBM released the POWER4 and discontinued the RS64 line.  The POWER4 merged the PowerPC (and POWER) instruction sets with the PowerPC-AS instruction set of the RS64.

IBM POWER4+ 1.2GHz - 2004

Now IBM had a single processor for both the RS/6000 line and the AS/400 line of computers.  The POWER4 was also an incredible boost in speed and now featured 2-cores on one die (the first non-embedded processor to do so).  Even the initial version did 1.1GHz.  L2 cache size was decreased to 1.4MB but moved on die.  L1 cache remained at 96kb.  To compensate for the reduced L2 cache size IBM added a 32mb off chip L3 cache.   The POWER4+ would eventually hit 1.9GHz.  In the picture on the left the 32MB of L3 cache is the large white chip in the upper right, while the dual core CPU is in the lower left.

POWER5 1.65GHz - 2004

In 2003 IBM further enhanced the POWER line and released the POWER5 processor.  Again a dual core processor running at 1.5-2.3GHz.  The POWER5 increased the on chip L2 cache to 1.9MB and moved the L3 cache on chip (though a separate die, like the Pentium Pro).  The L3 cache was also increased to 36mb.  As with the POWER4 the POWER5 was also offered in larger MCMs that integrated 4 processor dies, and 4 36mb L3 cache dies onto a single, large, MCM.  IBM has an excellent, in depth article on the differences of the POWER4 and POWER5 here.  IBM continues to develop the POWER line and currently is shipping system based on the 4GHz+ POWER7 processor.  The POWER8 successor is under development.

January 16th, 2011 ~ by admin

CPU of the Week: Intergraph Clipper C4 MCM


Fairchild developed the Clipper architecture in 1986, and sold it to Intergraph in 1987.  The design never enjoyed wide success and was only used in systems made by Integraph, as well as some by ‘High Level Hardware.’  The deign itself was RISC like and competed mainly with the Sun SPARC processors.

The final version was the C400 which was released in 1993 (preceded by the C100 and C300). Presumably there was a C200 but I have not seen any documentation on it.  The C400 ran at 50MHz (like the C300) and actually consisted of 3 separate chips. The CPU, the FPU and the CAMMU (Cache/Memory Management Unit).  Intergraph developed their own version of UNIX called CLIX to run on the clipper, and demonstrated a version of Windows NT that ran on the C400 as well. Ultimately the lack of software support, and the slow adoption killed the Clipper.  While Intergraph was designing the C5, Intel assured them a good supply of processors, and this convinced Intergraph to cancel the C5.

Intergraph C4 MCM

It was also available as a MCM (multi-chip-module) incorporating all three dies in a single ceramic package.  This is one of the nicest looking MCMs I have seen, unfortunately the bottom plate was missing when I got it, but the dies are at least visible.  I unfortunately am not sure which die is which so if you know, let me know.

January 6th, 2011 ~ by admin

The day has come, ARM + Microsoft Windows

Over a year ago we wrote about the need for native support of ARM cored processors by Windows (and not just Windows mobile).  Yesterday at the CES Microsoft officially announced it will be supporting ARM processors as well as ARM SoC’s in Windows 8, and demo’d several such systems.  This is very important to the landscape of processors.  Obviously software support will be initially lacking but this brings much needed competition to the PC market.

Intel and AMD have been competing with each other, and each other alone (with a few exceptions) for almost 10 years now. Bringing full fledged Windows to a new architecture is not unprecedented.  Windows NT 4 ran on x86, MIPS, PowerPC as well as the Digital Alpha.

Nvidia, already very talented in the GPU market, has been working on ARM processors for a couple years now with its Tegra line, so its not surprising that they have also announced development of a ARM based processor/GPU targeted for the desktop known as Project Denver.

VIA is also adding some more competition with the release of their first dual core processor, the Nano X2, based on the Isaiah architecture.  While not known for brute force, the Nano is known for its low heat and power sipping capabilities.

2011 is off to a great start and we look forward to seeing many new processors released, as well as old processors added to the museum