Hardware Reference
In-Depth Information
Besides support for 64-bit instructions, the biggest difference between the Athlon 64 and
64 FX and most other processors is the fact that their memory controller is built in. The
memory controller is traditionally normally part of the motherboard chipset North Bridge
or Memory Controller Hub (MCH) chip, but the Athlon 64 and 64 FX incorporate the
memory controller in the processor. This means that the typical CPU bus architecture is
different with these chips. In a conventional design, the processor talks to the chipset
NorthBridge,whichthentalkstothememoryandallothercomponentsinthesystem.Be-
cause the Athlon 64 and 64 FX have integrated memory controllers, they talk to memory
directly, but they also talk to the North Bridge for other system communications. Separ-
ating the memory traffic from the CPU bus allows for improved performance not only in
memorytransfers,butalsoinCPUbustransfers.ThemaindifferenceintheAthlon64and
64 FX is in the configurations of cache sizes and memory bus widths.
Following are the major features of the Athlon 64 design:
• Speeds ranging from 1.0GHz to 3.0GHz.
• Between 68.5 million transistors (512KB L2 cache versions) and 129 million transist-
ors (1MB L2 cache versions).
• 12-stage pipeline.
• DDR memory controller with ECC support integrated into the processor (instead of
the North Bridge or MCP, as in other recent chipsets).
• Socket 754 features single-channel memory controller; Socket 940, 939, and AM2
feature dual-channel memory controller.
• 128KB L1 cache.
• 512KB or 1MB of on-die full-speed L2 cache.
• Support for AMD64 (also called IA-32e or x86-64) 64-bit extension technology (ex-
tends 32-bit x86 architecture).
• Up to 3.2GBps (Socket 754) or 4GBps (Socket 940, 939, and AM2) Hypertransport
link to chipset North Bridge.
• Addressable memory size up to 1TB, greatly exceeding the 4GB or 64GB limit im-
posed by 32-bit processors.
• SSE2 (SSE plus 144 new instructions for graphics and sound processing).
• Multiple low-power states.
• 130-nanometer (see
Figure 3.37
), 90nm, or 65nm cores.
Figure 3.37
AMD Athlon 64 die (130-nanometer process, 106 million transistors, 193 sq. mm).