05.04 Hasyim Asyari 0 Comments

How Computers Work

2.1 – System Overview
2.2 – The Boot Process
2.3 – Hardware Components
2.4 – Memory Components
2.5 – Display Components
2.6 – Connector Components
2.7 – Storage Components
2.8 – Network Components
2.9 – System Resources
2.10 – Portable Devices

System Overview.

Input, Process, Output, and Storage.


  • Most operating systems provide functions to read and write data on files.
  • It then translates requests for operations on files into operations that the disk controller can carry out.
  • The operating system performs four basic operations,
  • Input
  • Processing
  • Output
  • Storage

Boot Process.

Initializing and Testing the System Hardware.
  • For an operating system to run, it must be loaded into the Random Access Memory (RAM).
  • When a computer is first turned on, it launches the bootstrap loader.
  • The primary functions of bootstrap are to test the computer hardware and to locate and load the operating system into RAM.
  • During the BIOS firmware routines, three major sets of operations happen:
  1. Power-On Self-Tests or POST
  2. Initialization
  3. BIOS moves the starting address and mode information into the DMA controller then Master Boot Record (MBR)
  • To test the computer hardware, the bootstrap program runs the power-on self-test or POST.
  • In this test, the central processing unit (CPU) checks itself first and then checks the computer system timer.
  • The POST checks the RAM by writing data to each RAM chip and then reading that data.
  • Any difference indicates a problem.
  • If the POST finds errors, it sends a message to the computer monitor.
  • If the POST finds errors that cannot be displayed on the monitor, it sends errors in the form of beeps.
  • The POST sends one beep and the screen begins to display OS loading messages once the bootstrap has determined that the computer has passed the POST.
  • The meaning of any beep code depends on the manufacturer of the BIOS. There are 3 major manufacturers of BIOS chips.
Loading the Operating System and Hardware Configuration.

  • The next step for the bootstrap program is to locate the OS and copy it to the computer RAM.
  • The bootstrap loader first looks to see if the OS boot file is located on a floppy drive.
  • If not, it looks for it on the hard disk.
  • If the operating system is not found on either the floppy drive or the hard disk, the bootstrap loader will look for the OS on the built-in CD ROM.
The Boot Sequence.


  • The number of events that happen in the boot process depends on the version of Windows and whether it is a cold boot or a warm boot.
  • Warm boot – Performed whenever the PC is restarted or reset with the power still on.
  • Cold boot – Starts whenever the PC power switch is turned on.

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