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MALLA REDDY COLLEGE OF ENGINEERING & TECHNOLOGY
(Autonomous Institution – UGC, Govt. of India) Recognized under 2(f) and 12 (B) of UGC ACT 1956
(Affiliated to JNTUH, Hyderabad, Approved by AICTE - Accredited by NBA & NAAC –‘A’ Grade - ISO 9001:2015 Certified)Maisammaguda, Dhulapally (Post Via. Hakimpet), Secunderabad – 500100, Telangana State, India
Department of Computer Science and Engineering
COMPUTER ORGANIZATION AND OPERATING SYSTEMS
LECTURE NOTES
B.Tech(III Year- I SEM)
Faculty Incharge HOD-CSE
MALLA REDDY COLLEGE OF ENGINEERING & TECHNOLOGY
Department of Computer Science and Engineering
Name of the subject : Computer organization and operating systems
Subject Code: R15A0569 Program: UG Branch : ECE Year : III Semester : I
No of Pages:
PREPARED BY: PREPARED BY:
Name: VELICHETY ALEKHYA Name: S.J.SRUTHI RANI YADAV Design. : Asst. Professor Design. : Asst. Professor
HOD PRINCIPAL
DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING
Vision To acknowledge quality education and instill high patterns of discipline making the students technologically superior and ethically strong which involves the improvement in the quality of life in human race. Mission To achieve and impart holistic technical education using the best of infrastructure, outstanding technical and teaching expertise to establish the students into competent and confident engineers. Evolving the center of excellence through creative and innovative teaching learning practices for promoting academic achievement to produce internationally accepted competitive and world class professionals.
PROGRAMME EDUCATIONAL OBJECTIVES (PEOs)
PEO1 – ANALYTICAL SKILLS
1.To facilitate the graduates with the ability to visualize, gather information, articulate, analyze, solve complex problems, and make decisions. These are essential to address the challenges of complex and computation intensive problems increasing their productivity. PEO2 – TECHNICAL SKILLS 2.To facilitate the graduates with the technical skills that prepare them for immediate employment and pursue certification providing a deeper understanding of the technology in advanced areas of computer science and related fields, thus encouraging to pursue higher education and research based on their interest. PEO3 – SOFT SKILLS 3.To facilitate the graduates with the soft skills that include fulfilling the mission, setting goals, showing self-confidence by communicating effectively, having a positive attitude, get involved in team-work, being a leader, managing their career and their life. PEO4 – PROFESSIONAL ETHICS
4.To facilitate the graduates with the knowledge of professional and ethical responsibilities by paying attention to grooming, being conservative with style, following dress codes, safety codes,and adapting themselves to technological advancements.
UNIT-
BASIC STRUCTURE OF COMPUTERS
Contents:
Computer Types
Functional Unit
Basic Operational concepts
Bus structures
Software performance
Multiprocessors and multi computers
Data Representation
Fixed point Representation
Floating- point Representation
Unit- I
Basic Structure of Computers
Computer Architecture in general covers three aspects of computer design namely: Computer Hardware, Instruction set Architecture and Computer Organization. Computer hardware consists of electronic circuits, displays, magnetic and optical storage media and communication facilities. Instruction set Architecture is programmer visible machine interface such as instruction set, registers, memory organization and exception handling. Two main approaches are mainly CISC (Complex Instruction Set Computer) and RISC (Reduced Instruction Set Computer) Computer Organization includes the high level aspects of a design, such as memory system, the bus structure and the design of the internal CPU. Computer Types
Computer is a fast electronic calculating machine which accepts digital input, processes it according to the internally stored instructions (Programs) and produces the result on the output device. The internal operation of the computer can be as depicted in the figure below:
Figure 1: Fetch, Decode and Execute steps in a Computer System
Functional Units
A computer in its simplest form comprises five functional units namely input unit, output unit memory unit, arithmetic & logic unit and control unit. Figure 2 depicts the functional units of a computer system.
Figure 2: Basic functional units of a computer Let us discuss about each of them in brief:
1. Input Unit: Computer accepts encoded information through input unit. The standard input device is a keyboard. Whenever a key is pressed, keyboard controller sends the code to CPU/Memory.
Examples include Mouse, Joystick, Tracker ball, Light pen, Digitizer, Scanner etc.
2. Memory Unit: Memory unit stores the program instructions (Code), data and results of computations etc. Memory unit is classified as: Primary /Main Memory
- Secondary /Auxiliary Memory
Primary memory is a semiconductor memory that provides access at high speed. Run time program instructions and operands are stored in the main memory. Main memory is classified again as ROM and RAM. ROM holds system programs and firmware routines such as BIOS, POST, I/O Drivers that are essential to manage the hardware of a computer. RAM is termed as Read/Write memory or user memory that holds run time program instruction and data. While primary storage is essential, it is volatile in nature and expensive. Additional requirement of memory could be supplied as auxiliary memory at cheaper cost. Secondary memories are non volatile in nature. Arithmetic and logic unit: ALU consist of necessary logic circuits like adder, comparator etc., to perform operations of addition, multiplication, comparison of two numbers etc. Output Unit: Computer after computation returns the computed results, error messages, etc. via output unit. The standard output device is a video monitor, LCD/TFT monitor. Other output devices are printers, plotters etc. Control Unit: Control unit co-ordinates activities of all units by issuing control signals. Control signals issued by control unit govern the data transfers and then appropriate operations take place. Control unit interprets or decides the operation/action to be performed. The operations of a computer can be summarized as follows: A set of instructions called a program reside in the main memory of computer.
The CPU fetches those instructions sequentially one-by-one from the main memory, decodes them and performs the specified operation on associated data operands in ALU. Processed data and results will be displayed on an output unit.
All activities pertaining to processing and data movement inside the computer machine are governed by control unit.
executed. The program counter keeps track of the execution of the program. It contains the memory address of the next instruction to be fetched and executed. There are n general purpose registers R0 to Rn-1 which can be used by the programmers during writing programs.
Figure 3: Connections between the processor and the memory
The interaction between the processor and the memory and the direction of flow of information is as shown in the diagram below:
Figure 4: Interaction between the memory and the ALU
BUS STRUCTURES
Group of lines that serve as connecting path for several devices is called a bus (one bit per line). Individual parts must communicate over a communication line or path for exchanging data, address and control information as shown in the diagram below. Printer example – processor to printer. A common approach is to use the concept of buffer registers to hold the content during the transfer.
Figure 5: Single bus structure
SOFTWARE
If a user wants to enter and run an application program, he/she needs a System Software. System Software is a collection of programs that are executed as needed to perform functions such as:
Figure 6 :User program and OS routine sharing of the processor
PERFORMANCE The total time required to execute a program is the most important measure of performance for a computer. (t0-t5 of earlier example). Compiler, instruction set and hardware architecture, program all have impact on performance.
Basic Performance Equation: The basic performance equation is given by T = (N * S) / R where T=execution time, N=number of instructions, S=average cycles per instruction, R=clock rate in cycles per second
CACHING
Commonly used data are copied to on-processor memory (cache) to reduce access time. Small memories can be made with higher speed than large ones. In a computer, we need both.
Figure 7: The processor cache
PIPELINING and SUPERSCALR OPERATION
Pipelining: Like a production line, instruction execution overlapped so greater parallelism is achieved. Superscalar operation: Execute several instructions simultaneously using multiple ALU‘s.
CISC vs RISC Reduced instruction set computer
- Large N, small S Complex instruction set computer
- Small N, large S COMPILER
Translates high level language such as C, C++ and Java to machine instructions. Aims to reduce N×S
PERFORMANCE MEASUREMENT
Benchmark refers to standard task used to measure how well a processor operates. To evaluate the performance of Computers, a non-profit organization known as SPEC-System Performance Evaluation Corporation employs agreed-upon application programs of real world for benchmarks. Accordingly, it gives performance measure for a computer as the time required to execute a given benchmark program. The SPEC rating is computed as follows
Data Representation Introduction The digital computer is a digital system that performs various computational tasks. The word digital implies that the information in the computer is represented by variables that take a limited number of discrete values. These values are processed internally by components that can maintain a limited number of discrete states. The decimal digits 0, 1, 2, 9, for example, provide 10 discrete values. The first electronic digital computers, developed in the late 1940s, were used primarily for numerical computations. In this case the discrete elements are the digits. From this application the term digital computer has emerged. In practice, digital computers function more reliably only if two states are used. Because of the physical restriction of components, and because human logic tends to be binary (i.e. true-or-false, yes-or-no statements), digital components that are constrained to take discrete values are further constrained to take only two values and are said to be binary.
Objectives: After studying this unit, the learner will be able to Explain various units of a digital computer
Understand different data types
Explain fixed and floating point number representation
Discuss various binary and error detection codes
Digital Computers Digital computers use the binary number system, which has two digits: 0 and 1. A binary digit is called a bit. Information is represented in digital computers in groups of bits. By using various coding techniques, groups of bits can be made to represent not only binary numbers but also other discrete symbols, such as decimal digits or letters of the alphabet. By the judicious use of binary arrangements and by using various coding techniques, the groups of bits are used to develop complete sets of instructions for performing various types of computations. In contrast to the common decimal numbers that employ the base 10 system, binary numbers use a base 2
system with two digits: 0 and 1. The decimal equivalent of a binary number can be found by expanding it into a power series with a base of
- For example, the binary number 1001011 represents a quantity that can be converted to a decimal number by multiplying each bit by the base 2 raised to an integer power as follows: 1 x 2^6 + 0 x 2^5 + 0 x 2^4 + 1 x 2^3 + 0 x 2^2 + 1 x 2^1 + 1 x 2^0 = 75 The seven bits 1001011 represent a binary number whose decimal equivalent is 75. However, this same group of seven bits represents the letter K when used in conjunction with a binary code for the letters of the alphabet. It may also represent a control code for specifying some decision logic in a particular digital computer. In other words, groups of bits in a digital computer are used to represent many different things. This is similar to the concept that the same letters of an alphabet are used to construct different languages, such as English and French. A computer system is sometimes subdivided into two functional entities: hardware and software. The hardware of the computer consists of all the electronic components and electromechanical devices that comprise the physical entity of the device. Computer software consists of the instructions and the data that the computer manipulates to perform various data-processing tasks. A sequence of instructions for the computer is called a program. The data that are manipulated by the program constitute the data base. A computer system is composed of its hardware and the system software available for its use. The system software of a computer consists of a collection of programs whose purpose is to make more effective use of the computer. The programs included in a systems software package are referred to as the operating system. They are distinguished from application programs written by the user for the purpose of solving particular problems. For example, a high-level language program written by a user to solve particular data-processing needs is an application program , but the compiler that translates the high- level language program to machine language is a system program. The customer who buys a computer system would need, in addition to the hardware, any available software needed for effective operation of the computer. The system software is an indispensable part of a total computer system. Its function is to compensate for the differences that exist between user needs and the capability of the hardware. The hardware of the computer is usually divided into three major parts as shown in Fig. 1.1.
Random Access Memory (RAM)
