MIPS Technologies R3000

MIPS R3000 is a 32-bit microprocessor that implements MIPS 1 instruction set architecture. MIPS 1 instruction set is very small as compared to instruction sets of other (80x86, 680x0, etc) microprocessors, as it includes only most commonly used instructions and supports very limited number of addressing modes. Small number of CPU instructions, as well as other instruction set features - fixed instruction length and only three different types of instruction formats - greatly simplify instruction decoding and processing. To speed-up processing even further the CPU employs 5-stage pipeline. Very efficient pipeline design allows the R3000 CPU execute most instructions at a rate close to 1 instruction per cycle.

In addition to the CPU core, the R3000 microprocessor includes Control Processor (CP), that contains Translation Lookaside Buffer and Memory Management Unit. The CP works as a co-processor. Besides the CP, the R3000 can also support external R3010 numeric co-processor and two other external co-processors.

The R3000 CPU does not include its own level 1 cache. Instead, the processor has on-chip Cache controller which controls separate external data and instruction caches. The size of each external cache can be as large as 256 KB. The CPU can access both caches during the same CPU cycle.