Phenom (pronounced as IPA:/finɒm/, as in the word phenomenon) is the AMD desktop processor line based on the K10 (not “K10h”) microarchitecture , or Family 10h Processors, as AMD calls them. Triple-core versions (codenamed “Toliman“) will be the Phenom 8000 series, quad cores (codenamed “Agena“) in the Phenom 9000 series, and high-end enthusiast versions (codenamed “Agena FX“) in the Phenom FX series. AMD considers the quad core Phenoms to be the first “true” quad core design, as these processors are a monolithic multi-core design (all cores on the same piece of silicon wafer), unlike Intel’s Core 2 Quad series which are a multi-chip module (MCM) design. The processors will be on the Socket AM2+ platform , with the exception of the high-end model which will only be available for Socket F+. The dual core K10 processors will still be named Athlon X2.

AMD has launched several models of the Phenom processor in 2007/2008.

Change of model nomenclatures

The model numbers of the new line of processors was changed from the PR system used in its predecessors, the Athlon 64 X2 family. The new model numbering scheme, for later released Athlon X2 processors, is a four digit model number with different family indicator as the first number , while some Athlon X2 processors used BE as prefix (example as Athlon X2 BE-2400) and some Sempron processors uses the LE prefix (example Sempron LE-1200), as follows:

Series number
Processor series Indicator
Phenom quad-core (Agena) 9
Phenom triple-core (Toliman) 8
Athlon dual-core (Kuma) 6
Athlon single-core (Lima) 1
Sempron single-core (Sparta) 1

TLB errata

Before Phenom’s release, it was discovered that a bug in the translation lookaside buffer (otherwise known as a TLB) in AMD’s quad-core processors could cause a system lockup in rare circumstances. Phenom is affected by this bug up to and including stepping “B2” and “BA”. There are BIOS and software workarounds to prevent this problem from occurring by disabling the TLB, although the workarounds typically employed incur a performance penalty of at least 10%.

This penalty was not accounted for in early pre-release previews of Phenom, so the performance of early Phenoms delivered to customers is expected to be somewhat below the benchmarks in these previews. Processors with the bug fixed will be named Phenom 9550 and 9650, with stepping “B3” and are supposed to arrive “mid to late Q1 2008.”

However, AMD Dresden has released a patch for the Linux Kernel to overcome this bug by software emulation of accessed- and dirty-bits causing little performance loss.

Future models

Starting the second half of 2008, AMD is expected to launch a series of 45 nm processors . As of October 2007, only the codenames are known to the public. They are Deneb FX for Phenom FX, Deneb for quad-core processors, Heka for triple-core Phenom processor and Regor for Athlon X2. These processors are expected to be available in late 2008 to early 2009, with the support of DDR3 memory and are expected to have larger shared L3 cache(6 Mb) as well as the implementation of Socket AM3 for single-processor systems and Socket G3MX for dual-processor Quad FX platform

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