What is the Front Side Bus?
The Front Side Bus (FSB) is the connecting path between the CPU and other key components such as system memory.
The Front Side Bus is also called the Data Bus and the Processor Side Bus (PSB).
Front Side Bus Widths of Various CPU's
| CPU | Front Side Bus Width |
|---|---|
| 8088 | 8 |
| 8086 | 16 |
| 80286 | 16 |
| 80386SX | 16 |
| 80386DX | 32 |
| 80486 | 32 |
| AMD 5x86 | 32 |
| Pentium | 64 |
| AMD K6 | 64 |
| Pentium Pro | 64 |
| Celeron | 64 |
| Pentium II | 64 |
| Pentium III | 64 |
| AMD Duron | 64 |
| AMD Athlon | 64 |
| AMD Athlon XP | 64 |
| Pentium 4 | 64 |
| Itanium | 64 |
| AMD Athlon 64 | 64 |
Competing Front Side Bus Technologies
The EV6 Front Side Bus
AMD uses the EV6 Front Side Bus in its Athlon and Athlon XP CPU's.
Athlon and Athlon XP CPU's with the EV6 bus are able to transfer data over the Front Side Bus twice per processor cycle.
The AGTL+ Front Side Bus
Intel uses the AGTL+ Front Side Bus in its Pentium 4 processors.
Pentium 4's with AGTL+ are able to transfer data over the Front Side Bus four times per processor cycle.
However, the AGTL+ bus is shared among all of the systems CPU's. The EV6 bus is a point-to-point bus, meaning that the full bandwidth of the bus is available to every CPU.
HyperTransport
AMD Athlon64, AthlonFX, and Opteron CPU's utilize the HyperTransport Bus.
These CPU's move the memory controller into the CPU, effectively eliminating the Front Side Bus.
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