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Higher ComputingSystems Components of a computer system Hardware Central Processing Unit (CPU) Central Processing Unit (CPU) Memory Memory Input and Output.

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Presentation on theme: "Higher ComputingSystems Components of a computer system Hardware Central Processing Unit (CPU) Central Processing Unit (CPU) Memory Memory Input and Output."— Presentation transcript:

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2 Higher ComputingSystems Components of a computer system Hardware Central Processing Unit (CPU) Central Processing Unit (CPU) Memory Memory Input and Output Devices Input and Output DevicesSoftwareData

3 Higher ComputingSystems Components of a computer system Computer hardware provides the physical mechanisms to store, manipulate and input /output data.Computer hardware provides the physical mechanisms to store, manipulate and input /output data. Software provides instructions to tell the hardware what tasks to performSoftware provides instructions to tell the hardware what tasks to perform Data in the computer may be representing numbers, characters, graphics etc but is always kept in a form that the hardware and software can manipulate.Data in the computer may be representing numbers, characters, graphics etc but is always kept in a form that the hardware and software can manipulate.

4 Higher ComputingSystems CPU performs actual processing of data.CPU performs actual processing of data. Data and programs are stored in memory, and moved to and from CPU as required.Data and programs are stored in memory, and moved to and from CPU as required. Data travels between system components along electronic pathways, (sets of wires), called buses. Data travels between system components along electronic pathways, (sets of wires), called buses. Basic concepts - Hardware

5 Higher ComputingSystems We will look at: We will look at: Four Box diagram Four Box diagram CPU CPU Memory Memory Registers and their role Registers and their role Processing speed Processing speed

6 Higher ComputingSystems n Three major components of the CPU: ALU, Control unit and Registers. n The Arithmetic Logic Unit (ALU) operates on binary data to perform all arithmetic and logical functions. + - * / + - * / = <> = <> AND OR NOT AND OR NOT Rotate Shift Rotate Shift n Control unit fetches and interprets instructions in memory and generates signals to control all other system components.

7 Higher ComputingSystems Four Box Diagram Input Output Backing Store Processor Memory (RAM and ROM) CPU

8 Higher ComputingSystems Memory Purpose of memory is data storage. A hierarchy of memory exists. Purpose of memory is data storage. A hierarchy of memory exists. data required for immediate manipulation by CPU is stored in small areas of fast access memory within CPU called registers. data required for immediate manipulation by CPU is stored in small areas of fast access memory within CPU called registers. data required for active program is generally stored in primary memory, commonly called RAM. data required for active program is generally stored in primary memory, commonly called RAM. data which may be required at later time generally stored in secondary storage e.g. on disk, tape, or CD-Rom. data which may be required at later time generally stored in secondary storage e.g. on disk, tape, or CD-Rom.

9 Higher ComputingSystems Memory: characteristics Capacity : no of bits, bytes or words in module. Addressable unit - 1 word. Word size may be 8, 16, 32 bits ; (1 byte = 8 bits) Capacity : no of bits, bytes or words in module. Addressable unit - 1 word. Word size may be 8, 16, 32 bits ; (1 byte = 8 bits) Unit of transfer : RAM = 1 word ; Disk = 1 block Unit of transfer : RAM = 1 word ; Disk = 1 block access time or speed - time required to read from memory location. Tradeoff between quantity, cost and speed. As speed increases so does cost. access time or speed - time required to read from memory location. Tradeoff between quantity, cost and speed. As speed increases so does cost. Also know as Primary Storage Also know as Primary Storage

10 Higher ComputingSystems n Registers: very fast memory internal to CPU providing temporary storage places for data being manipulated. n System clock generates regular pulses to synchronize all system events and determine the speed at which processing can occur. n Basic measure of system performance is clock speed, measured in megahertz (millions of cycles per second)

11 Higher ComputingSystems Semiconductor main memory is made up of RAM and ROM Primary memory is made up of RAM and ROM Types include: RAM (Random Access Memory) RAM (Random Access Memory) ROM (Read Only Memory) ROM (Read Only Memory)

12 Higher ComputingSystems ROM- SECONDARY STORAGE Read Only Memory Permanent non-volatilePermanent non-volatile Software and data fixed during chip manufactureSoftware and data fixed during chip manufacture Cannot be written toCannot be written to All computers have some ROM to load the Operating System into RAM (bootstrap loader)All computers have some ROM to load the Operating System into RAM (bootstrap loader)

13 Higher ComputingSystems ALU Control Unit CPU Primary Memory – CPU exchanges data with memory via the registers such as IR and PC. Registers Secondary Memory i.e. hard drive CD R/W Floppy How the components interact


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