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Computer Systems. Nat 4/5 Computing Science Computer Structure: Lesson 1: Processor Structure. Lesson Aims. By the end of this lesson: Pupils at will be able to: Label a computer system in terms of a 5 block diagram Describe the phrase ‘word length’ Describe the purpose of a processor
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Computer Systems Nat 4/5 Computing Science Computer Structure: Lesson 1: Processor Structure
Lesson Aims • By the end of this lesson: • Pupils at will be able to: • Label a computer system in terms of a 5 block diagram • Describe the phrase ‘word length’ • Describe the purpose of a processor • List and describe the parts of a processor: • Control Unit, ALU, registers • Describe what a bus is and does
Nat 4/5 A Basic Computer System • This is known as the 5 block diagram. Backing Storage Processor Input Devices Output Devices Memory
Nat 4/5 The 5 Block Diagram • Input Devices • These are devices that enter data INTOthe computer. i.e. Keyboard and mouse • Output Devices • These are devices that generate output FROMthe computer i.e. printer. • Memory • There are two types of memory. RAM and ROM (more on this later) • Backing Storage • This is required to store permanent copies of our files.
Nat 4/5 TheProcessor • The processor is the ‘brain’ of the computer. • It is the piece of equipment that actually performs the instructions required. • It can be shown in the following diagram: Processor Control Unit Arithmetic and Logic Unit (ALU) Registers
ProcessorParts Nat 4/5 Control Unit This controls the order of execution and the timing of instructions Arithmetic and Logic Unit (ALU) This performs the calculations for the processor. It also carries out the Logical decisions. Registers These are temporary stores of information, at best they will store a few bytes of information.
Nat 4/5 32 bit and 64 bit computing? • You often hear a processor being described as 32 bit or 64 bit. • This is usually referring to the ‘word length’ of the computer • This is the largest binary number that the processor can manipulate in one operation.
What does a bus do? A bus is a collection of wires which can carry data Nat 4/5 Processor Main Memory Control Unit Data Bus RAM Address Bus ALU ROM Registers
Nat 4/5 Buses • Data Bus • The data bus is used to carry data to and from the CPU and Memory. • It will hold a binary word. • Address Bus • This carries the address of the memory location that is being used
Summary The CPU (Central Processing Unit) is the heart of the computer The CPU has 3 main parts • Control Unit • Controls the timing and order of execution • Arithmetic and Logic Unit (ALU) • Performs the arithmetical and logical functions • Registers • Temporary stores of information Word length is the length of the biggest binary number that the processor can process in one operation Nat 4/5 Mnemonic – CAR(s)