The PC Hierarchy

The complex relationship between computer hardware and software.

HARDWARE: Physical Components are called Hardware. The hardware includes all of the circuits, drives, expansion boards etc.

BIOS: BIOS is a set of small programs that are designed to operate major PC subsystem. The BIOS runs a power-on self-test (POST) program each time the PC is initialized. POST checks the major subsystems before attempting to load an operating system.

OPERATING SYSTEM: The operating system serves two very important functions in the modern PC. First, an OS interacts with, and provides an extension to the BIOS. This is high-level file handling and disk-control functions. It is this large number of disk-related functions. Second, an OS forms an “environment” (or shell) through which applications can be executed, and provides a user interface.

APPLICATIONS: A computer is to execute applications. An OS loads and allows the user to launch the desired application(s). As the application requires system resources during run-time.

Boot Process

1. Switch on the Computer

2. System can check POST Operation

3. After POST, send Boot instruction to CPU to Boot Disk From ROM BIOS .

4. Drive can read the FloyyDisk/Hard Disk Boot sector.

5. Boot File are IO.SYS, MSDOS.SYS can be transfored to RAM and Activated the System

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Power - On Self - Test (POST)

1. Switch on your PC, start a process called the POST ( power-on self test ) From CPU.

2. The CPU uses the address to find and invoke the ROM BIOS boot program, which is a series of system checks. The CPU first checks itself and the POST program.

3. The CPU sends signals over the system bus. The circuits that connect all the components with each other, to make sure that they are all functioning.

4. The CPU also checks the system’s timer, or clock, which is responsible for make sure all the PC’s operations function in a synchronized.

5. The POST tests the memory contained on the display adapter and the video that control the display.

6. The POST runs a series of tests to ensure that the RAM functioning properly.

7. The CPU verifies that the keyboard is attached properly and determines whether any keys have been pressed.

8. The POST sends signals over paths on the bus to the floppy/ hard disk drives and which drives are available for OS.

Read-only memory (ROM)

One type of memory is that, Read Only Memory, as it is not erased when the system is switched off. It is also called BIOS ROM. Basic input and Output System. It is made by Complementary metal–oxide–semiconductor (CMOS) programmers or data stored in this memory can’t be altered or modified.

Types of ROM PROM (Programmable Read Only Memory) : Stored programs can be Read for special applications.

EPROM (Erasable Programmable Read Only Memory) memories are PROMs that can be deleted. These chips have a glass panel that lets ultra-violet rays through. This is why this type of PROM is called erasable.

EEPROM (Electrically Erasable Read Only Memory) memories are also erasable PROMs, but unlike EPROMs, they can be erased by a simple electric current, meaning that they can be erased even when they are in position in the computer.

Switch Mode Power Supply

Switch Mode Power Supply (SMPS)
Switch mode power supplies(SMPS) are an extraordinary of high frequency alternative. These are the Switching Regulators offers higher efficiency then liner regulators. The Power Supply SMPS can step-up, down and invert the input voltage

Advantages of Switch Mode Power Supply
-Change the output to a different voltage level then the input ( step-up or step-down).
-Isolate the output from the input.
-Provide the user with a means to vary the output
-Can get constant output at variable input.
-Stabilize the output against the influence of:-
-Output short circuit protected.

Applications of Switch Mode Power Supply
-SMPSs are having wide range of applications some of them are -
-Security systems (Close Circuit Cameras)
-Where the size and wight very less is required
-Audio and vedio application

MOTHERBOARD Power Connector Types with Color Code

Inside CPU