Topic 1 Systems Architecture (1.1.1-1.2.2)

Central Processing Unit

to execute out instructions and process data

• Control Unit (CU) • Arithmetic Logic Unit (ALU) • The Cache

To execute program instructions by following the fetch-decode-execute cycle

Does all the calculations and contains the Accumulator Register

Stores regularly used data so the CPU can access it quickly if it’s needed. If the CPU requests data, it checks the cache first, if it doesn’t have it, it checks the RAM

It’s slower than the registers but faster than the RAM

Small storage locations in the CPU which are super-quick to read/write to

A system where the CPU runs programs stored in memory

• Program Counter (PC) • Accumulator • Memory Address Register (MAR) • Memory Data Register (MDR)

stores the address of the next instruction to be fetched from memory increments during each cycle to point to the next instruction

stores the address of the data to be fetched from or the address where the data is to be stored

stores the data that is fetched from or written to memory

stores the results of the calculations or operations carried out by the Arithmetic Logic Unit (ALU)

It stores it in the same memory

the Fetch-Decode-Execute cycle

• the instruction/data is fetched from memory • the instruction/data is decoded • the instruction/data is executed -the ALU performs logical and arithmetic calculations

A computer system built into another device to control or manage a specific function

It means they are built to do one specific job. This makes them cheaper, easier to design, and more efficient.

• microwave • washing machine • traffic lights • fitness tracker • digital camera • smart thermostat • printer

Random Access Memory

Primary memory in a computer which can be both read and written to. Is is volatile memory.

Memory that loses its data when it doesn’t have power

used to store running programs, documents or files while the computer is on