Mainframes and Supercomputers Overview

Mainframes

• Powerful computers designed for large-scale processing of transactions
• Typically used in organizations with high demands for data storage and processing
• Housed in a central location with multiple user terminals connected
• Require dedicated space due to their size and need for temperature and humidity control
• Major vendors include IBM and DEC
• Examples include MEDHA, SPERRY, IBM, DEC, HP, and HCL

Supercomputers

• Most powerful and expensive computers
• Used for complex scientific applications requiring significant processing power
• Utilize multiprocessor technology for fast calculations
• Designed for specific tasks
• Cost depends on processing capabilities and configuration
• Speed is measured in gigaflops, teraflops, and petaflops
  • Gigaflops = 10^9 arithmetic operations per second
  • Teraflops = 10^12 arithmetic operations per second
  • Petaflops = 10^15 arithmetic operations per second
• Examples include PARAM, EKA, and BLUE GENE/P

Computer Generations

• Generations are categorized based on technological advancements
• Five generations of computers recognized
  • First generation (1942-1955)
    • Vacuum tube technology
    • Performed calculations in milliseconds
    • Bulky size and complex design
    • Generated significant heat
    • Required constant hardware maintenance
    • Air-conditioned rooms required
    • Difficult and expensive to produce
    • Limited commercial use
    • Examples: ENIAC, EDVAC, EDSAC
  • Second generation (1955-1964)
    • Transistor technology
    • Smaller size than first generation systems
    • Less heat generation than first generation computers
    • Consumed less power than first generation systems
    • Calculations in microseconds
    • Air-conditioning still required
    • Easier to configure than first generation computers

Input Devices

• Devices that allow data to be entered into a computer
• Classified into standard, pointing, and special input devices
  • Standard Input Devices
    • Keyboard
      • Most commonly used input device
      • Similar to a typewriter for data entry
      • Consists of keys for alphabets, numbers, and special characters
      • Divided into general purpose and special purpose keyboards
        • General purpose keyboards
          • Standard keyboards used in personal computers
          • Contain keys for all types of applications
          • Typically have 101 keys
          • Divided into alphanumeric keypad, numeric keypad, arrow keys, function keys, and special keys
          • Alphanumeric keypad: contains alphabets, numbers, and special characters
          • Numeric keypad: contains numbers 0-9 and mathematical symbols
          • Arrow keys: control cursor movement
          • Function keys: provide shortcuts in software
          • Special keys: perform specific tasks
            • Tab: inserts spaces or moves the cursor to a defined position
            • Enter: generates output of a command
            • Space: creates a space between words
            • Backspace: deletes the character to the left of the cursor position
  • Pointing Devices
    • Mouse
    • Trackball
    • Joystick
    • Light pen
    • Touchscreen
  • Special Input Devices
    • Microphone
    • Scanner
    • Camera

Memory Chips

• EPROM (Erasable Programmable Read Only Memory): can be electrically programmed, erased, and reprogrammed
• EEPROM (Electrically Erasable Programmable Read Only Memory): can be electrically programmed, erased, and reprogrammed

Ports

• Serial Port (Asynchronous Port or RS-232-C)
  • Sends and receives data using two lines (ideal for phone circuits)
  • Slower communication speed
  • Higher signal travel capacity
• Parallel Port (Centronics or Printer Port)
  • 8-bit data transfer for faster communication (ideal for printers)
  • Lower signal travel capacity than serial ports
• USB Port (Universal Serial Bus)
  • New standard for connecting peripherals like keyboards, mice, scanners, printers, webcams
  • Operates at two speeds: 1.5 Mbps and 12 Mbps
  • Auto-loads necessary drivers for connected devices.
• PS/2 Port
  • Developed by IBM for connecting mice and keyboards to PCs
  • Supports a six-pin connector
  • Also called a mouse port

Cables

• Serial Cable
  • Typically used for RS-232 communication
  • Transmits information serially between two devices
  • Connector type depends on the port used
  • Working length is limited by noise interference
  • Cheap to purchase, easy to join and connect
  • Suitable for unbalanced data standards
• Parallel Cable
  • Transmits information between devices in parallel data transfer

CD-ROM (Compact Disc - Read Only Memory)

• Non-erasable backing storage for large amounts of data
• Shiny silver disk with a storage capacity of around 650 MB
• Data is written using a laser beam
• Known as WORM (Write Once Read Many) technology
• Advantages:
  • Low cost per bit
  • No need for mechanical read/write heads
  • Compact in size
  • Lightweight
• Disadvantages:
  • Read-only storage medium (data cannot be erased or changed)
  • Slower access speed than magnetic disks

DVD (Digital Versatile Disc)

• Optical disk storage for large data quantities, including high-quality movies
• Utilizes the same principle as CD-ROM
• Data recorded layer by later for greater storage capacity
• Total capacity of 8.5 GB
• Advantages:
  • Larger capacity than CD-ROM
• Disadvantages:
  • More expensive than CD-ROM
  • Prone to damage if not handled properly

Zip Disk

• Removable magnetic disk for reading and writing data
• Similar to floppy disks but faster and with larger capacity
• Available in sizes of 100 MB and 250 MB
• Advantages:
  • Easy to use
  • Larger capacity than floppy disks
  • Faster than floppy disks
  • Easy to carry
• Disadvantages:
  • Expensive
  • Slower data transfer between disk and computer

Pen Drive

• Small printed circuit board encased in a durable plastic or metal casing
• Easily transportable and portable
• Uses a standard-A connector for direct connection to a computer

Number Systems

• Hexadecimal (Base 16):
  • Each digit represents a value from 0-15 (0-9, A-F)
  • The value increases from left to right: 1, 16, 256, 65536...
  • Conversion from decimal to hexadecimal:
    • Divide the decimal number by 16 repeatedly until the quotient is 0.
    • The remainders, read from bottom to top, represent the hexadecimal value.
  • Conversion from hexadecimal to decimal:
    • Multiply each digit by its corresponding power of 16 (starting from the rightmost digit).
    • Add the results to obtain the decimal equivalent.
  • Conversion from binary to hexadecimal:
    • Group binary digits into sets of 4.
    • Convert each set of 4 binary digits to its hexadecimal equivalent.
  • Conversion from hexadecimal to binary:
    • Convert each hexadecimal digit to its 4-bit binary representation.
    • Concatenate the binary digits.
  • Conversion from hexadecimal to octal:
    • Convert each hexadecimal digit to its 4-bit binary representation.
    • Group the binary digits into sets of 3 (adding leading zeros if necessary).
    • Convert each set of 3 binary digits to its octal equivalent.