chapter 1 operating system

• What's an operating system?

  a program that acts as an intermediary between a user of a computer and the computer hardware
• what are the operating system goals?

  • execute user programs and make solving user problems easier
  • make the computer system convenient to use
  • use the computer hardware in an efficient manner
• What are the FOUR components of computer system?

  1. Hardware
  2. Operating system
  3. Application programs
  4. Users
• what does hardware provide?

  basic computing resources
• CPU, memory, I/O devices are examples of..?

  hardware
• operating system

  controls and coordinates the use of hardware among various applications and users
• What's the definition of application programs?

  -define the way in which the system resources are used to solve the computing problems of the users

  • ex:Word processors, compilers, web browsers, database system, video games
• what are examples of hardware?

  CPU, memory, I/O devices
• who are 'Users'?

  People, machines, other computers
• Draw the diagram of four components of a computer system

  answer in slide page 4
• what operating system do

  depends on pov

  users want convenience, ease of use

  • don't care about resource utilization
• what is resource utilization?


  the measure of how much of your available resources you are currently using
• resource utilization can help..?

  plan how to utilize your resources more effectively to ensure that your organization is being as productive a possible
• users of dedicated systems such as workstations have dedicated resources but frequently use shared resources from...?

  server
• handheld computers are resource-poor, optimized for...?

  usability and battery life
• what computers have little or no user interface?

  embedded computers in devices and automobiles
• OS is a resource allocator that..?

  • manages all resources
  • decides between conflicting requests for efficient and fair resource use
• OS is a control program that...?

  controls the execution of programs to prevent errors and improper use of the computer
• What is the one program running at all times on the computer?

  the kernel
• kernel is a computer program at the core of a computer's..?

  operating system and generally has complete control over everything in the system (pg7)
• kernel is also responsible for..?

  preventing and mitigating conflicts between different processes
• whats a bootstrap program?

  the first code that is executed when the computer system is started
• the entire operating system depends on the ... to work correctly as it loads the operating system

  bootstrap program
• bootstrap program is loaded at...?

  power up or reboot
• bootstrap program...

  • is typically stored in ROM or EPROM, generally known as firmware
  • initializes all aspects of system
  • loads operating system kernel and starts execution
• draw the diagram of computer startup (hint:bootstrap program)

  answer in pg 8
• Computer System Organization

  computer system operation

  • one or more CPUs, device controllers connect through a common bus that provides access to shared memory
  • concurrent execution of CPU and devices competing for memory cycles
• The basic computer has eight registers, a memory unit, and a control unit . Paths must be provided to transfer information from one register to another and between memory and registers
• draw the computer system operation diagram

  answer in pg 9
• What is known as a bus?

  a pair of signal lines that facilitate the transfer of multi-bit data from one system to another
• draw the common bus diagram

  answer in pg 10
• 1.3 computer system operation (pg11)

  • I/O devices and CPU can execute concurrently (at the same time)
  • each device controller is in charge of a particular device type
  • each device controller has a local buffer
  • CPU moves data from/to main memory to/from local buffers
  • I/O device is from local buffer to controller
  • device controller informs CPU that it's finished its operation by causing an interrupt
• whats a buffer in operating system?

  region of a memory used to store a data temporarily while it's being moved from one place to another
• whats an interrupt?

  a signal emitted (discharged) by a device attached to a computer or from a program within the computer
• interrupt

  -requires the OS to stop and figure out what to do next

  -temporarily stops or terminates a service or a current process
• 1.3.1 pg 13

  • device controller informs CPU that it's finished its operation by causing an interrupt from either the hardware or software
  • hardware may trigger an interrupt at any time by sending a signal to the CPU, usually by way of the system bus
  • software may trigger an interrupt by executing a special operation called a system call (or a monitor call)
  • -a trap or exception is a software-generated interrupt caused either by an error or a user request
• the programmatic way in which a computer program requests a service from the operating system on which it is executed is called a ...?


  system call
• • When the CPU is interrupted, it stops what it is doing and immediately transfers execution to a fixed location.
  • The fixed location usually contains the starting address where the service routine for the interrupt is located
  • The interrupt service routine executes; on completion, the CPU resumes the interrupted computation.
• programs and data is not possible to reside in main memory permanently because of ...?

  1. main memory is usually too small to store all needed programs and data permanently
  2. main memory is a volatile (likely to change) storage device that loses its contents when power is turned off or otherwise lost
• what do most computer systems provide as an extension of main memory?


  secondary storage