chapter 1 compArchi

• Computer architecture


  Attributes of a computer system that have a direct impact on the logical execution of a program
• Computer organization


  How the operational units of a computer system are interconnected
• Computer architecture


  Considered first before computer organisation
• Computer architecture


  Represents interface between hardware and software
• Computer organisation


  Decided after computer architecture
• Computer organisation


  Represents components of a connection in a computer system
• Computer architecture


  • Comprises logical functions such as instruction sets, registers, data types, and addressing modes
• Computer organisation


  • Consists of physical units like circuit designs, peripherals, and adders
• Central Processing Unit (CPU)


  Controls the operation of a computer and perform data processing function i.e. calculation
• Input device


  Input program text, data and command to the computer
• Output device


  Send result of data processing to the user
• Memory


  Hold program and data for access of the CPU while processing is taking place
• Data processing


  Computer must be able to process data which may take a wide variety of forms and the range of processing
• Data movement


  Computer must be able to move data for processing and data communication
• Data storage


  Once processed, computer stores data either temporarily or permanently
• Control


  Manages the computer resources and controls the performance of the functional units
• Von Neumann architecture


  Basic computer architecture conforms to the general principles established by John von Neumann
• Von Neumann architecture


  • Memory holds both programs and data
  • Instructions are fetched from memory and executed sequentially
  • The processor decodes and executes an instruction, before cycling around to fetch the next instruction
  • The cycle continues until no more instructions are available
• Control unit


  Controls the operations of components like ALU, memory and input/output devices
• Arithmetic Logic Unit (ALU)


  Allows arithmetic (add, subtract, etc.) and logic (AND, OR, NOT, etc.) operations to be carried out
• Registers


  High speed storage areas in the CPU that store small amounts of data that are needed during processing
• Memory hierarchy


  Loading data from permanent memory (hard drive), into the faster and directly accessible temporary memory (RAM), allows the CPU to operate much quicker
• Von Neumann bottleneck


  CPU and memory speed disparity, where CPUs processing speed is much faster in comparison to the main memory, so the CPU needs to wait longer to obtain instruction from the memory
• Similarities between computer systems

  • The basic hardware components and design are very similar for large and small computers
• Differences between computer systems

  • Differ primarily in the number of cores, the amount of memory, speed, capacity, and the selection of input and output(I/O) devices provided
• Computer


  A programmable electronic device that can accept input; store data; and retrieve, process and output information
• Father of Computer


  • Charles Babbage (1791-1871)
  • Mathematician and Scientist
  • Created Difference Engine (mechanical computer that could do basic computations)
  • Created Analytical Engine (solving any mathematical problem and storing data in an indefinite memory)
• First Programmer


  • Ada Lovelace (1815-1852)
  • Mathematician and Writer
  • Work with Charles Cabbage on mechanical general-purpose computer
• Computer Generations


  • 1st Generation (Vacuum Tubes)
  • 2nd Generation (Transistors)
  • 3rd Generation (Integrated Circuits)
  • 4th Generation (Microprocessor)
  • 5th Generation (AI)
• 1st Generation (Vacuum Tubes)


  An electronic device that controls the flow of electrons in a vacuum
• 1st Generation (Vacuum Tubes)

  • Punch cards, paper tape, and magnetic tape were the other basic components used for I/O devices and memory needs
  • Machine language was developed for the use of computers
  • Vacuum tubes were much larger in size at the time, they eventually led to larger computer sizes which took up a lot of space in one room
• 1st Generation (Vacuum Tubes)

  • ENIAC
  • UNIVAC-1
  • EDVAC
  • ENIVAC
• ENIAC


  • Electronic Numerical Integrator and Computer
  • First operational electronic general-purpose computer
  • Designed by John W. Mauchly and J. Presper Eckert at the University of Pennsylvania
  • Uses nearly 18,000 vacuum tubes which over 167 square meters (1800 square feet) of floor space to keep cool
  • Couldn't store any programming commands in its memory
  • Executable instructions composing a program were embodied in the separate units of ENIAC, which were plugged together to form a route through the machine for the flow of computations
  • Could only do one kind of program at a time, and to change the program meant completely rewiring it
• EDVAC


  • Electronic Discrete Variable Automatic Computer
  • First stored program computer
  • Designed by John W. Mauchly and J. Presper Eckert at the University of Pennsylvania
  • Represented binary systems rather than decimal systems
  • Needed far fewer vacuum tubes than ENIAC's because EDVAC's primary memory used more-compact and less-expensive mercury delay lines instead of vacuum tubes
• EDSAC


  • Electronic Delay Storage Automatic Calculator
  • Developed by Maurice Wilkes at Cambridge University
  • Designed to be used for scientific calculations
  • First computer to use a form of memory known as random-access memory (RAM)
  • Maurice invented subroutines, an essential component of modern programming that allows developers to reuse bits of existing code to simplify the act of writing software
• 2nd Generation (Transistors)

  Computers made in the second generation were completely based upon transistors, not on vacuum tubes
• 2nd Generation (Transistors)


  • Magnetic cores were used as the primary memory and magnetic tape and magnetic disks as secondary storage devices
  • COBOL and FORTRAN are employed as assembly languages and programming languages
  • Transistors, like other electronic components, needed to be soldered together. As a result, the more complex the circuits became, the more complicated and numerous the connections between the individual transistors and the likelihood of faulty wiring increased
• IBM 1620


  • A general-purpose, stored-program data processing system for small businesses, research and engineering departments of large companies, and schools requiring solutions to complex problems in the areas of engineering, research, and management science
  • This system was based on the transistors and its complete circuitry was transistorized
• 3rd Generation (Integrated Circuits)

  The integrated circuit (IC) is a semiconductor material, that contains thousands of transistors miniaturized in it
• 3rd Generation (Integrated Circuits)

  • Punch cards were replaced by mouse and keyboard
  • High-level programming languages such as FORTRON-II to IV, COBOL, and PASCAL PL/1 were utilized