Front-side Bus - History

History

The term came into use by Intel Corporation about the time the Pentium Pro and Pentium II products were announced, in the 1990s.

"Front side" refers to the external interface from the processor to the rest of the computer system, as opposed to the back side, where the back-side bus connects the cache (and potentially other CPUs).

A FSB is mostly used on PC-related motherboards (including personal computers and servers), seldom with the data and address buses used in embedded systems and similar small computers. This design represented a performance improvement over the single system bus designs of the previous decades, but sometimes is still called the "system bus".

Front-side buses usually connect the CPU and the rest of the hardware via a chipset, which Intel implemented as a northbridge and a southbridge. Other buses like the Peripheral Component Interconnect (PCI), Accelerated Graphics Port (AGP), and memory buses all connect to the chipset in order for data to flow between the connected devices. These secondary system buses usually run at speeds derived from the front-side bus clock, but are not necessarily synchronized to it.

In response to AMD's Torrenza initiative, Intel opened its FSB CPU socket to third party devices. Prior to this announcement, made in Spring 2007 at Intel Developer Forum in Beijing, Intel had very closely guarded who had access to the FSB, only allowing Intel processors in the CPU socket. The first example was Field-programmable gate array (FPGA) co-processors, a result of collaboration between Intel-Xilinx-Nallatech and Intel-Altera-XtremeData (which shipped in 2008).