You probably know by now that the Raspberry Pi uses an ARM processor. In particular, the Raspberry Pi model B uses the Broadcom BCM2835 system on a chip (SoC). The BCM2835 is a member of the ARM11 family. Its name is the ARM1176JZF-S. (Whew!)

Like all computers, the BCM2835 has an internal processor structure called its “microarchitecture”. The word “architecture” refers to the machine features that are visible to a programmer — things like the instruction set. The microarchitecture refers to the building blocks in the guts of the machine, or more properly, in the guts of a specific implementation (BCM2835) of an architectural family (ARM11 or ARMv6).

The microarchitecture can have a big effect on program performance. Compiler writers, for example, study the microarchitecture in order to build compilers that generate the best possible code for the microarchitecture. As we’ll see in later posts, application programmers can also take steps to tune their programs for the underlying microarchitecture. Tuning is important on Raspberry Pi because at 700 MHz, this machine is running its heart out!

Today, I added a page that summarizes the characteristics of the BCM2835 (ARM11) microarchitecture. Please check out the info! We will revisit this page when I discuss profiling and tuning.