Is the Cell Based on Power4 or Power5

Because this IBM link says Xbox 360 Tri Core is based on Power5 processors

http://domino.research.ibm.com/comm/research.nsf/pages/r.verification.innovation.html

The POWER4 series places two complete CPU cores (otherwise similar to the POWER3) on a single chip, speeds it up, and adds high-speed connections to up to three additional pairs of POWER4 CPUs. They can be placed together on a motherboard to produce an 8-CPU SMP building block. When processing requires high throughput instead of high code complexity, one of a pair of cores can be turned off so that the remaining cores have the entire bus and L3 cache to themselves. The POWER4, even in single form, is considered by many to be the most powerful CPU available.


IBM rolled out the POWER5 processor in 2004. The 1.9 GHz version posted the highest uniprocessor SPECfp score of any shipping chip. The POWER5 powers the i5 and p5 eServers. Improvements in the POWER5 over the POWER4 include: a larger L2 cache, a memory controller on the chip, simultaneous multithreading which appears to the operating system as multiple CPUs, advanced power management, dedicated single-tasking mode, Hypervisor (virtualization technology), and eFuse (hardware re-routing around faults). Ravi Arimilli, IBM's chief microprocessor designer has said: "The POWER5 chip is more of a midrange design that can drive up to the high end and then down to things like blades." IBM servers built with the POWER5 processor offer virtualization features: logical partitioning and micro partitioning. Up to ten LPARs (logical partitions) can be created for each CPU, the biggest 64-Way system can run 256 independent operating systems. Memory, CPU-Power and I/O can be dynamically moved between partitions.

Source: Wikipedia

EDIT: Cell processor also uses Power5:

X-Gen was developed by IBM's Haifa Research Lab. It has been a crucial element in the verification of the majority of the PowerPC-based systems in IBM, including the Cell processor, the POWER-based systems used at the heart of IBM's iSeries, pSeries, and OpenPower eServers, and the chip that drives Microsoft's XBOX 360.
 
I don't think anyone who hasn't actually worked on Cell silicon itself can answer this question definitivly, but I really doubt it as 1)POWER4 was fairly slow, even shrinking it to 90nm wouldn't of got you to 3.2Ghz and 2)was a mainframe server CPU built for dependability rather than speed (you can't just cut stuff out of a CPU and have it ready for another market, many things in the design are dependant on what it'll be used for (ie. POWER4 was meant for large MP systems so had lots of logic and massive caches dedicated to hiding latency, you sure don't see any of either in Cell...)).

My WAG would be the PPE is a very generic but new design that was heavily automated and then touched up by hand to reduce costs and time to market that applied lessons learned from work done on the 970FX...

EDIT: That quote does not state that Cell uses POWER5 at all, just mentions POWER PC which is the ISA that Cell is using...
 
hasanahmad said:
Because this IBM link says Xbox 360 Tri Core is based on Power5

Neither the Xbox tricore nor Cell is based on Power3, Power4 or Power5. Both the PPE on Cell and the cores in the Xbox CPU is using a newly designed core.
 
mesyn191 said:
EDIT: That quote does not state that Cell uses POWER5 at all, just mentions POWER PC which is the ISA that Cell is using...

Nor does the first link state that the X-CPU uses Power5.
 
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