2 Hardware and Software

• Mainframe computers are powerful computers serving several terminals
• Uses of mainframe computers

  they are used for large scale transaction processing and batch processing

  they are also used for statistical analysis, industry statistics, and consumer statistics

  they are often used to host business databases that can be accessed by the business and thousands of consumers simultaneously through a web interface

  they need to have RAS: RELIABILITY, AVAILABILITY, AND SERVICEABILITY
• Mainframe computers are measured in MIPS - MILLIONS OF INSTRUCTIONS PER SECOND
• Advantages of mainframe computers

  designed to have RAS so makes them more reliable than regular computers

  designed to last at least 10 years

  able to store and process extremely large amounts of data

  more than one operating system can be used at once which improves the overall performance

  hardware failures notified immediately so replacements can be made
• Disadvantages of mainframe computers

  high cost so they are only used by large organizations

  a lot of space required to install

  temperature must be maintained so that it doesn't become too hot

  interface is command drive which can be difficult to understand

  requires trained staff for maintenance
• Supercomputers are large computers with parallel processing to complete highly complex tasks quickly
• Supercomputers are designed to carry out large complex calculations

  they will run very few computer programs and focus on executing instructions as quickly as possible for one purpose

  they run at maximum capacity so that their full power is used to process data
• Uses of supercomputers

  they are required for research in quantum mechanics, weather forecasting, and climate research

  they process billions of observations from weather monitoring stations, satellites, weather balloons, and radar
• Supercomputers are measured in FLOPS - FLOATING POINT OPERATIONS PER SECOND
• Advantages of supercomputers

  solves bigger problems

  runs more problems in a shorter time

  processes things immediately
• Disadvantages of supercomputers

  high cost so they are only used by large organizations

  processing huge amounts of data so they need massive external storage devices

  a lot of space required to install

  temperature must be maintained so it does not get too hot

  requires trained staff for maintenance
• System software is software needed to operate a computer system
• An operating system is a software that manages the hardware within a computer system.
• An operating system manages hardware by carrying out tasks such as:

  • allocating memory to software
  • sending data and instructions to output devices
  • responding to input devices such as when a key is pressed
  • opening and closing files on storage devices
  • sending error messages to applications or users
  • dealing with user logons and security
• The operating system sits between the hardware and application software
• A device driver is a software that comes with an external hardware component and sends customized instructions to the specific component
• Compilers translates high-level programming language into an executable file in machine code
• The process of compilation

  • program is compiled
  • whole source code is translated into the executable file at once
  • in executable format, it can only run on operating systems for which the compiler is translated for
• Advantages of a compiler

  faster run speed

  more robust
• Disadvantages of a compiler

  source code compiled on one platform will not run on another

  takes long to complete
• An interpreter translates and executes a high-level programming language one line at a time
• Uses of an interpreter

  used to translate macros or application-based script languages

  also used for testing programs
• Advantages of an interpreter

  helps find errors easily as it is executed line by line
• Disadvantages of interpreter

  takes more time to execute than a compiler
• COMPILER translates source code into object code all at once


  INTERPRETER translates source code into object code one line at a time
• COMPILER: object code will only work on the operating system it has been compiled for


  INTERPRETER: source code can be translated into object code for more than one operating system
• COMPILER: object code is ready to be executed without delay


  INTERPRETER: object code has to be generated, so additional time is added to execution time
• COMPILER: errors are reported after compilation is completed


  INTERPRETER: errors are reported so they are found during interpretation
• Linkers combine the object files together to form a single executable file
• Utility software is software that performs some sort of maintenance on the computer system
• Examples of utility software

  anti virus: software that deals with other threats such as adware and spyware

  if the anti virus monitor detects any unusual behavior or signs of viruses then it prevents them from being executed so they cannot cause damage to files or programs

  it also scans the system for viruses that may already exist
• Advantage of anti virus

  continually monitors the system for viruses and malware

  if unusual behavior detected, it will prevent them from being executed so they cannot damage files or programs
• Disadvantage of anti virus

  no customer support without purchasing premium subscription

  anti virus uses a lot of resources and can slow down the computer system
• Examples of utility software

  backup: creates a second copy of data and programs that are in storage
• Advantage of backup

  backs up all important files without losing any information
• Disadvantage of backup

  if the data needing backup is large, it may require a lot of time

  if data is large, it may require a lot of storage
• Examples of utility software

  data compression: reduce the original size of files so that they use up less storage space
• Advantage of data compression

  takes up less storage as file size reduces

  can be transferred from one location to another quickly
• Disadvantage of data compression

  slower to open the compressed file than the uncompressed file
• Examples of utility software

  disk defragmentation: reorganizes all the files so that each file is kept together

  it does this by moving fragmented parts of files to free space on the disk

  then it moves the defragmented files to a place where the whole file is kept together