1.2 Processor Performance

The maximum possible memory addresses of the system

Data can be sent both ways along the bus

• Clock speed • The number of cores in the processor • The amount and type of cache memory

The faster the clock speed, the faster a computer can fetch, decode and execute instructions

A sequence of frequent on and off signals are used to synchronise the operations of the components (actions are carried on the rising edge of the clock, which take a fixed number of cycles to complete)

Each core in theory can process different instructions simultaneously making its own fetch-decode-execute cycle (although some software may not be able to take full advantage of all four processors

Using several processor cores working at the same time

Instructions are processed sequentially

A small amount of superfast (but expensive) memory that stores data and instructions that have been recently been used by the processor

Instruction cache and data cache so that data and instructions can be fetched simultaneously

A technique used to improve performance, by example overlapping stages in the fetch-exectue cycle, or by breaking down the stages in an arithmetic instruction

• An instruction enters the pipeline, and as soon as one stage has been completed, another instruction enters the pipeline • A third instruction then enters before either of the others is completed

• Clock speed • Corse • Size and type of cache • Size of address bus which determines maximum size of RAM • Size of data bus determines the maximum size of an operand in an instruction • Pipelining is used to improve efficiency