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A detailed overview of the five generations of computers, highlighting their key characteristics, technologies, and advancements. It explores the evolution of computer architecture and organization, from the early vacuum tube-based systems to the modern ulsi microprocessor-based computers. The document also delves into the concepts of computer organization and architecture, explaining their differences and their roles in computer design and development. It further discusses the various types of computers based on their operating principles, including digital, analog, and hybrid computers.
Typology: Exercises
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Unit – I (10 Lectures)
STRUCTURE OF COMPUTERS : Computer types, functional units, basic operational concepts, Von‐Neumann architecture, bus structures, software, performance, multiprocessors and multicomputer Book: Carl Hamacher, Zvonks Vranesic, SafeaZaky (2002), Computer Organization, 5th edition, McGraw Hill: Unit-1 Pages: 1-
Data representation, fixed and floating point and error detecting codes. Book: M. Moris Mano (2006), Computer System Architecture, 3rd edition, Pearson/PHI, India: Unit-3 Pages: 67-
REGISTER TRANSFER AND MICRO‐OPERATIONS: Register transfer language, register transfer, bus and memory transfers, arithmetic micro‐operations, logic micro‐operations, shift micro‐operations, arithmetic logic shift unit. Book: M. Moris Mano (2006), Computer System Architecture, 3rd edition, Pearson/PHI, India: Unit-3 Pages: 93-
Computer Architecture: Computer Architecture deals with giving operational attributes of the computer or Processor to be specific. It deals with details like physical memory, ISA (Instruction Set Architecture) of the processor, the number of bits used to represent the data types, Input Output mechanism and technique for addressing memories. Computer Organization: Computer Organization is realization of what is specified by the computer architecture .It deals with how operational attributes are linked together to meet the requirements specified by computer architecture. Some organizational attributes are hardware details, control signals, peripherals. EXAMPLE: Say you are in a company that manufactures cars, design and all low-level details of the car come under computer architecture (abstract, programmers view), while making it’s parts piece by piece and connecting together the different components of that car by keeping the basic design in mind comes under computer organization (physical and visible).
Computer Organization Computer Architecture
The period of first generation was 1946-1959. The computers of first generation used vacuum tubes as the basic components for memory and circuitry for CPU (Central Processing Unit). These tubes, like electric bulbs, produced a lot of heat and were prone to frequent fusing of the installations, therefore, were very expensive and could be afforded only by very large organizations. In this generation mainly batch processing operating system were used. Punched cards, paper tape, and magnetic tape were used as input and output devices. The computers in this generation used machine code as programming language.
The main features of first generation are: Vacuum tube technology Unreliable Supported machine language only Very costly Generated lot of heat Slow input and output devices Huge size Need of A.C. Non-portable Consumed lot of electricity Some computers of this generation were: ENIAC EDVAC UNIVAC IBM- IBM-
Second generation The period of second generation was 1959-1965. In this generation transistors were used that were cheaper, consumed less power, more compact in size, more reliable and faster than the first generation machines made of vacuum tubes. In this generation, magnetic cores were used as primary memory and magnetic tape and magnetic disks as secondary storage devices. In this generation assembly language and high-level programming languages like FORTRAN, COBOL were used. The computers used batch processing and multiprogramming operating system.
The main features of second generation are: Use of transistors Reliable in comparison to first generation computers Smaller size as compared to first generation computers Generated less heat as compared to first generation computers Consumed less electricity as compared to first generation computers Faster than first generation computers Still very costly A.C. needed Supported machine and assembly languages Some computers of this generation were: IBM 1620 IBM 7094 CDC 1604 CDC 3600 UNIVAC 1108 Third generation
The period of fourth generation was 1971-1980. The computers of fourth generation used Very Large Scale Integrated (VLSI) circuits. VLSI circuits having about 5000 transistors and other circuit elements and their associated circuits on a single chip made it possible to have microcomputers of fourth generation. Fourth generation computers became more powerful, compact, reliable, and affordable. As a result, it gave rise to personal computer (PC) revolution. In this generation time sharing, real time, networks, distributed operating system were used. All the high-level languages like C, C++, DBASE etc., were used in this generation.
The main features of fourth generation are: VLSI technology used Very cheap Portable and reliable Use of PC's Very small size Pipeline processing No A.C. needed Concept of internet was introduced Great developments in the fields of networks Computers became easily available Some computers of this generation were: DEC 10 STAR 1000 PDP 11 CRAY-1(Super Computer) CRAY-X-MP(Super Computer)
Fifth generation
The period of fifth generation is 1980-till date. In the fifth generation, the VLSI technology became ULSI (Ultra Large Scale Integration) technology, resulting in the production of microprocessor chips having ten million electronic components. This generation is based on parallel processing hardware and AI (Artificial Intelligence) software. AI is an emerging branch in computer science, which interprets means and method of making computers think like human beings. All the high-level languages like C and C++, Java, .Net etc., are used in this generation. AI includes: Robotics Neural Networks Game Playing Development of expert systems to make decisions in real life situations. Natural language understanding and generation.
The main features of fifth generation are: ULSI technology Development of true artificial intelligence Development of Natural language processing Advancement in Parallel Processing Advancement in Superconductor technology More user friendly interfaces with multimedia features Availability of very powerful and compact computers at cheaper rates Some computer types of this generation are: Desktop Laptop NoteBook UltraBook
and provides logical operations, while the analog component normally serves as a solver of differential equations.
Classification digital Computer based on size and Capability Based on size and capability, computers are broadly classified into Micro Computers(Personal Computer) A microcomputer is the smallest general purpose processing system. The older pc started 8 bit processor with speed of 3.7MB and current pc 64 bit processor with speed of 4.66 GB. Examples: - IBM PC s, APPLE computers Microcomputer can be classified into 2 types:
Notebook : - These computers are as powerful as desktop but size of these computers are comparatively smaller than laptop and desktop. They weigh 2 to 3 kg. They are more costly than laptop.
Palmtop (Hand held) : - They are also called as personal Digital Assistant (PDA). These computers are small in size. They can be held in hands. It is capable of doing word processing, spreadsheets and hand writing recognition, game playing, faxing and paging. These computers are not as powerful as desktop computers. Ex: - 3com palmV.
Wearable computer : - The size of this computer is very small so that it can be worn on the body. It has smaller processing power. It is used in the field of medicine. For example pace maker to correct the heart beats. Insulin meter to find the levels of insulin in the blood.
Workstations:- It is used in large, high-resolution graphics screen built in network support, Engineering applications(CAD/CAM), software development desktop publishing
Classification based on number of microprocessors Based on the number of microprocessors, computers can be classified into a) Sequential computers and b) Parallel computers a) Sequential computers : - Any task complete in sequential computers is with one microcomputer only. Most of the computers (today) we see are sequential computers where in any task is completed sequentially instruction after instruction from the beginning to the end. b) Parallel computers : - The parallel computer is relatively fast. New types of computers that use a large number of processors. The processors perform different tasks independently and simultaneously thus improving the speed of execution of complex programs dramatically. Parallel computers match the speed of supercomputers at a fraction of the cost.
Classification based on word-length A binary digit is called “BIT”. A word is a group of bits which is fixed for a computer. The number of bits in a word (or word length) determines the representation of all characters in these many bits. Word length leis in the range from 16-bit to 64-bitsf or most computers of today.
Classification based on number of users Based on number of users, computers are classified into: - Single User : - Only one user can use the resource at any time.
Multi User : - A single computer shared by a number of users at any time.
Network : - A number of interconnected autonomous computers shared by a number of users at any time.
•Input: Whatever is put into a computer system. •Data: Refers to the symbols that represent facts, objects, or ideas. •Information: The results of the computer storing data as bits and bytes; the words, umbers, sounds, and graphics. •Output: Consists of the processing results produced by a computer. •Processing: Manipulation of the data in many ways. •Memory: Area of the computer that temporarily holds data waiting to be processed, stored, or output. •Storage: Area of the computer that holds data on a permanent basis when it is not immediately needed for processing. •Assembly language program (ALP) – Programs are written using mnemonics •Mnemonic –Instruction will be in the form of English like form •Assembler –is a software which converts ALP to MLL (Machine Level Language) •HLL (High Level Language) –Programs are written using English like statements •Compiler -Convert HLL to MLL, does this job by reading source program at once •Interpreter –Converts HLL to MLL, does this job statement by statement •System software –Program routines which aid the user in the execution of programs eg: Assemblers, Compilers •Operating system –Collection of routines responsible for controlling and coordinating all the activities in a computer system
Hardware** , consisting of its physical devices (CPU, memory, bus, storage devices, ...) Software , consisting of the programs it has (Operating system, applications, utilities, ...)
FUNCTIONAL UNIT
A computer consists of five functionally independent main parts input, memory, arithmetic logic unit (ALU), output and control unit.
Functional units of computer
Input device accepts the coded information as source program i.e. high level language. This is either stored in the memory or immediately used by the processor to perform the desired operations. The program stored in the memory determines the processing steps. Basically the computer converts one source program to an object program. i.e. into machine language.
Finally the results are sent to the outside world through output device. All of these actions are coordinated by the control unit.
Input unit: -
Number of bits in each word is called word length of the computer. Programs must reside in the memory during execution. Instructions and data can be written into the memory or read out under the control of processor. Memory in which any location can be reached in a short and fixed amount of time after specifying its address is called random- access memory (RAM).
The time required to access one word in called memory access time. Memory which is only readable by the user and contents of which can’t be altered is called read only memory (ROM) it contains operating system.
Caches are the small fast RAM units, which are coupled with the processor and are often contained on the same IC chip to achieve high performance. Although primary storage is essential it tends to be expensive. 2 Secondary memory: - Is used where large amounts of data & programs have to be stored, particularly information that is accessed infrequently. Examples: - Magnetic disks & tapes, optical disks (ie CD-ROM’s), floppies etc.,
Arithmetic logic unit (ALU):- Most of the computer operators are executed in ALU of the processor like addition, subtraction, division, multiplication, etc. the operands are brought into the ALU from memory and stored in high speed storage elements called register. Then according to the instructions the operation is performed in the required sequence.
The control and the ALU are may times faster than other devices connected to a computer system. This enables a single processor to control a number of external devices such as key boards, displays, magnetic and optical disks, sensors and other mechanical controllers.
Output unit:- These actually are the counterparts of input unit. Its basic function is to send the processed results to the outside world.
Examples:- Printer, speakers, monitor etc.
Control unit:- It effectively is the nerve center that sends signals to other units and senses their states. The actual timing signals that govern the transfer of data between input unit, processor, memory and output unit are generated by the control unit.
