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Functions of major hardware components of a computer system. Objective. At the end of the lesson, students should be able to: Explain the functions of the major hardware components of a computer system. Central Processing Unit (CPU). Handles the processing of the computer.
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Objective • At the end of the lesson, students should be able to: • Explain the functions of the major hardware components of a computer system.
Central Processing Unit (CPU) • Handles the processing of the computer. • Controls the transfer of data between memory and other devices. • Consists of two (2) smaller units – Control Unit (CU) and Arithmetic Logic Unit (ALU)
Control Unit • This unit controls the overall operations of the CPU. • Directs the operation of components that process the data. • Controls the flow of programs and data in and out of primary memory (main memory) • Read and interpret program instructions • Control the flow of information to and from all components of the computer.
Arithmetic Logic Unit • Performs arithmetic operations. These operations include: addition, subtraction, division, multiplication, etc. • Performs logical operations. These operations include: reasoning and performing the comparisons necessary to make decisions.
Primary storage • Also referred to as main memory/ immediate access storage. • Is directly accessible to the CPU • Holds data and instructions that are currently being processed (temporary). • There are two (2) types of primary storage (both use chips): • Random Access Memory (RAM) • Read Only Memory (ROM)
Random Access Memory • Contents are temporary and are volatile ( lost when the computer is turned off) • Stores the instructions and data for currently running programs and the operating system • Computer can access data held in RAM immediately
Read Only Memory • Contents are permanent and non-volatile (not lost when the computer is turned off). • Used to store commands such as those used to boot up the computer. • These instructions are read, cannot be changed and are available every time the computer boots up. • These instructions are programmed into the ROM chips by the manufacturer.
Secondary Storage • Also referred to as backing storage or auxilliary storage. • Refers to media and methods used to keep programs, data and information available for later retrieval. • Not built on chips. Some examples are: • Hard disks Magnetic tape • Floppy disks Microflim • CD’s / DVD’s
Input Devices • These devices are used to enter commands and data into the computer. • Several devices are available each with its own applications, advantages and disadvantages.
Output Devices • These devices are used to display information that has been processed to the users. • There are two types of output devices: • Hardcopy (permanent) – it is tangible. E.g. Data printed on paper • Softcopy (temporary) – such as displays on a screen or speech from a speech synthesizer
Peripheral devices • These are devices that make up the computer system apart from the motherboard, its associated electronics and main memory.
Peripheral devices • E.g • Input Devices – keyboard, mouse, joystick, OMR (Optical Mark Reader), OCR (Optical Character Reader), MICR (Magnetic Ink Character Reader). • Storage Devices – magnetic tape drive, hard drive, floppy drive. • Output Devices – printers, VDU (Visual Display Unit), speakers.
References • Oxford Information Technology for CXC CSEC by Glenda Gay, Ronald Blades