The second generation (Paris/Palermo core) was based on the architecture of the Socket 754 Athlon 64. Some differences from Athlon 64 processors include a reduced cache size (either 128 or 256 KiB L2), and the absence of AMD64 support in earlier models. Apart from these differences, the Socket 754 Sempron CPUs share most features with the more powerful Athlon 64, including an integrated (on-die) memory controller, the HyperTransport link, and AMD's NX bit feature.
In the second half of 2005, AMD added 64-bit support (AMD64) to the Sempron line. Some journalists (but not AMD) often refer to this revision of chips as Sempron 64 to distinguish it from the previous revision. AMD's intent in releasing 64-bit entry-level processors was to extend the market for 64-bit processors, which at the time of Sempron 64's first release, was a niche market.
As AMD rolls out its newest Sempron processor line, many readers are asking us if the reduced cache Socket 754 Sempron 3100+ really compares with already shipping Athlon 64 single channel solutions. Today we take two single channel, 1.8GHz processors with differing L2 cache and compare them in the same Linux benchmarks we have used in the past. The Athlon 64 2800+ and the Sempron 3100+ are nearly identical processors, except for the 256KB cache difference. There is also a $20 delta between the two retail products, so today we decide if the $20 difference between the two processors is worth the sacrafice of level two cache and 64-bit addressing. We have provided benchmarks of another 1.8GHz 32-bit processor from AMD, as well as the Athlon 64 3000+ for reference only.
However, since last June AMD decided to activate the 64-bit extensions on socket 754 Sempron processors. Because of that there are Sempron processors on the market that have these instructions and processors that dondrs"t have them. How can we detect if a Sempron CPU has the 64-bit instruction set?
