Unit - 1 Basic Computer Architecture P. Sugin Benzigar

Fundamentals of Computers What is a Computer? A computer is an electronic device that manipulates information, or "data." It has the ability to store, retrieve, and process data. You can use a computer to type documents, send , and browse the internet. You can also use it to handle spreadsheets, accounting, database management, presentations, games, and more.

Computer components there are 2 basic components 1. Hardware 2. Software

how do computers work ??? Any device which can store, retrieve and process data needs something to control it. Softwares.... the ones that control the physical computer or (Hardware) eg. programs running on Thermometers, Optometrist devices, Mobile phones, computers, CARS (ESP), Bikes (ABS). contd......

how do computers work ??? all the data from all the peripheral devices are processed by central processing unit so the central processing unit is the brain of computer the CPU is in the computer is in the mother board and often reffered as processor or core eg. pentium 4, core2duo, i3, i

more on CPU the processors also determine the efficiency of the hardware. every processor can do a specific amount of work in a specific amount of time. the speed of the processor is measured in GHZ (giga hertz) speed = frequency / second

block dia. of how processor works hard disk/ instruction from key board/ mouse/ printer... RAM cache memory processor

Memory the memory of the computer is classified into 2 1. primary - stores info. temporialy for faster access 2. secondary or auxilary- for permanent use eg of primary memory RAM eg of secondary memory Hard disk

peripheral devices what are peripheral devices devices that cannot operate independently but will do fine with the help of a processor or an OS or any device that provides input to the computer and may or may not get output from the computer eg. printer, key board, mouse

more on peripheral devices Inorder to make the peripheral devices communicate with the computer each peripheral device has its own driver A driver is a software the can make a communication bridge between the device and the computing device the drivers may vary with devices and OS Eg. USB devices, printers, scanners, camera

more on peripheral devices Certain devices may not need drivers eg. mobile phones, Card readers with the advent in OS, they can be treated as external storage devices

Block diagram of PC

PROCESS

MEMORY CPU

MAIN MEMORY SECONDARY MEMORY MEMORY

INPUT UNIT Computer receives data and instructions through the Input Unit. The input unit consists of one or more input devices. Input devices include:  Keyboard  Mouse  Joystick  Scanner

FUNCTIONS OF INPUT UNIT Accept the data and instructions from the outside world. Convert it to a form that the computer can understand. Supply the converted data to the computer system for further processing.

OUTPUT UNIT Computer provides information and results of computation to the outside world through the Output Unit. The output unit consists of one or more output devices. Output devices include:  Monitor  Printer

FUNCTIONS OF OUTPUT UNIT Accept the results produced by the computer. (These are in a coded form.) Convert it to a form that the outside world can understand. (OR, Converts it into human readable form.) Supply the converted results to the outside world.

CENTRAL PROCESSING UNIT CPU It is the brain of the computer. The ALU and the Control Unit (CU) of a computer system are jointly known as the central processing unit. CPU performs actual processing of data, according to instructions from programs.

3 MAIN PARTS OF CPU CONTROL UNIT (CU) ARITHMETIC LOGIC UNIT (ALU) REGISTERS ( Registers are small high speed storage areas. ) Block Diagram

FUNCTIONS OF CPU It performs all calculations. It takes all decisions. It controls all units of the computer.

CONTROL UNIT It controls all other units in the computer. It is the central nervous system of the computer that controls and synchronizes its working.

FUNCTIONS OF CONTROL UNIT It instructs the input unit, where to store the data after receiving it from the user. It controls the flow of data and instructions from the storage unit to ALU. It also controls the flow of results from the ALU to the storage unit. The control unit determines the sequence in which computer programs and instructions are executed. The control unit is also capable of shutting down the computer when the power supply detects abnormal conditions.

ARITHMETIC LOGIC UNIT All calculations are performed in the Arithmetic Logic Unit (ALU) of the computer. Whenever calculations are required, the control unit transfers the data from memory to ALU. Once the computations are done, the results are transferred to the memory by the control unit and then it is send to the output unit for displaying results.

FUNCTIONS OF ALU It performs all arithmetic operations (addition, subtraction, multiplication, and division). It performs all logic operations (Logic operations test various conditions encountered during processing and allow for different actions to be taken based on the results. ) It does comparison and takes decision.

STORAGE UNIT The storage unit of the computer holds data and instructions that are entered through the input unit, before they are processed.

FUNCTIONS OF STORAGE UNIT It received the data and instructions required for processing from the input unit. It stores the intermediate results. It stores the final results before these results are released to the output unit. It saves data for later use.

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