What is a computer? A computer may be defined as a machine which accepts data from an input device, processes it by performing arithmetical and logic operations in accordance with a program of instructions and returns the results through an output unit. A computer is basically an electronic machine operating on current. | 1 COMPUTER SYSTEM COMPUTER SYSTEM BOOK I COMPUTER SYSTEM FUNDAMENTALS. Chapter 1 INTRODUCTION TO COMPUTER. Question 1. What is a computer A computer may be defined as a machine which accepts data from an input device processes it by performing arithmetical and logic operations in accordance with a program of instructions and returns the results through an output unit. A computer is basically an electronic machine operating on current. Question 2. Components of a Computer system A computer system comprises of the following components 1. Central Processing Unit CPU . - CPU is the heart of the whole sys 2 - CPU consists of the control unit arithmetic logic unit accumulator program counter instruction register memory address register memory data register status register general purpose register CU ALU ACC PC IR MAR MDR SR - The function of each components of CPU Control unit control and co_ordinate all hardware functions of the CS. examine and decode all program instructions to the computer and initiate their execution by sending the appropriate signals. ALU performs all arithmetic addition subtraction multiplication division exponentiation and logic comparision two values functions required by computer. ACC holds the first operand of the temporary result of the ALU. PC contains the add of the next instruction to be excuted. IR contains the current instruction to be executed. Main memory MAR holds the address location to or from which data is to be transferred MDR contains the data to be written to or read out of the addressed location. SR keeps track of the status of the accumalator. General Purpose Register for general purpose procedures. Please refer to diagram for an illustratin of the basic components of the CPU. 3 CPU i N ------------- t --------J Control unit J J E i-------- Arithmetic Logic Unit R -------------------------- J i n i Accumulator_ j I I A Program Couter L i i Instruction Register B ------------------------------1-- i u -----------i .
