Flexibility of high-performance caches and memory management schemes are strengths of the MIPS architecture. The MIPS64 architecture extends these advantages with well-deﬁned cache control options. The size of the instruction and data caches can range from 256 bytes to 4 MB. The data cache can employ either a write-back or write-through policy. A no-cache option can also be speciﬁed. The memory management mechanism can employ either a TLB or a Block Address Translation (BAT) policy. With a TLB, the MIPS64 architecture meets the memory management requirements of Linux, AndroidTM, Windows® CE and other historically popular operating systems.
The addition of data streaming and predicated operations supports the increasing computation needs of the embedded market. Conditional data move and data prefetch instructions are standardized, allowing for improved system-level data throughput in communication and multimedia applications.
Fixed-point DSP-type instructions further enhance multimedia processing. These instructions that include Multiply (MUL), Multiply and Add (MADD), Multiply and Subtract (MSUB), and “count leading 0s/1s,” previously available only on some 64-bit MIPS processors, provide greater performance in processing data streams such as audio, video, and multimedia without adding additional DSP hardware to the system.
Powerful 64-bit ﬂoating-point registers and execution units speed the tasks of processing some DSP algorithms and calculating graphics operations in real-time. Paired-single instructions pack two 32-bit ﬂoating-point operands into a single 64-bit register, allowing Single Instruction Multiple Data operations (SIMD). This provides twice as fast execution compared to traditional 32-bit ﬂoating-point units. Floating point operations can optionally be emulated in software.
The MIPS64 architecture features both 32-bit and 64-bit addressing modes, while working with 64-bit data. This allows reaping the beneﬁts of 64-bit data without the extra memory needed for 64-bit addressing. In order to allow easy migration from the 32-bit family, the architecture features a 32-bit compatibility mode, in which all registers and addresses are 32-bit wide and all instructions present in the MIPS32 architecture are executed.