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

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

Motherboard

ATX Motherboard features

The ATX is a best feature of the Baby-AT and

LPX motherboard designs, with many new enhancements and features. The ATX form factor is a Baby-AT motherboard turned sideways in the chassis, along with a modified power supply location and connector.

ATX improved on the Baby-AT and LPX motherboard designs in several major areas:
· Built-in double high external I/O connector panel.
· Single main keyed internal power supply connector.
· Relocated CPU and memory.
· Relocated internal I/O connectors.
· Improved cooling.
· Lower cost to manufacture.

Motherboard Form Factors

The most important component in a PC system is the main board or motherboard. The various types of motherboards available and those components typically contained on the motherboard interface connectors. Several common form factors are used for PC motherboards. The form factor refers to the physical dimensions (size and shape) as well as certain connector, screw hole, and other positions, type of case the board will fit.
motherboard form factors are:
Obsolete Form Factors
Baby-AT
Full-size AT
LPX (semiproprietary)
Modern Form Factors
ATX
Micro-ATX
Flex-ATX
NLX
WTX (no longer in production)
All Others
Proprietary designs
Industry-Standard Motherboard Form Factors
Form Factor Use
ATX Standard desktop, mini-tower, and full-tower systems; most common form factor today; most flexible design for power users, enthusiasts, low-end servers/ workstations, and higher-end home systems; ATX boards support up to seven expansion slots
Mini-ATX A slightly smaller version of ATX that fits into the same case as ATX. Many so called ATX motherboards are actually mini-ATX motherboards; mini-ATX boards support up to six expansion slots
Micro-ATX Mid-range desktop or mini-tower systems
Flex-ATX Least expensive or low-end small desktop or mini-tower systems; entertainment or appliance systems
NLX Corporate desktop or mini-tower systems; fast and easy serviceability
WTX Mid- to high-end workstations and servers (withdrawn)

MOTHER BOARD Features

1) LPX (12-pin) power supply connector
2) 5-pin DIN keyboard connector
3) PS/2 mouse port header cable connector
4) IDE host adapter cable connectors (2)
5) 32-bit PCI expansion slots (3)
6) BIOS chip
7) Combo PCI/ISA expansion slot
8) USB port header cable connector
9) COM (serial) ports header cable connectors (2)
10) LPT (parallel) port header cable connector
11) Floppy controller cable connector
12) ATX (20-pin) power supply connector
13) CPU fan power connector
14) 72-pin SIMM sockets (2)
15) 168-pin DIMM sockets (3)
16) AGP video card slot
17) VIA Apollo MVP 3 chipset (2 chips)
18) L2 cache memory (1MB total from 2 chips)
19) Super Socket 7 CPU socket
20) Connectors for case speaker, reset button, and other front panel devices
21) Case fan power connector
22) ISA expansion slots (3)
23) CR2032 battery for maintaining CMOS (RTC/RAM)
24) Voltage regulator assembly
25) CPU temperature sensor
26) CPU fan power connector

Chipsets

A chipset is a set of highly optimized, tightly inter-related ICs and circuits which, taken together, handle virtually all of the support functions for a motherboard. It is includes the CPU, the main memory, the secondary cache, other devices situated on the ISA, PCI, and AGP buses, IDE, SATA, FDD. The chipset also controls data flow to and from hard disks, and other devices connected to the IDE channels.
CPUs and hardware features are depending up on a PC. New chipsets must be developed to implement those functions. For example, the Intel 430HX chipset supports the Pentium CPU and EDO RAM. Their 430VX chipset supports use of the Pentium CPU, the Universal Serial BUS and SDRAM.

The chipset manufacturers are Intel, VIA, SIS, and Opti.

RAM Types and its uses

SDRAM (Synchronous DRAM)
P-III systems used to 3.3 volt, 168-pin SDRAM DIMMs. SDRAM started out running at 66 MHz. SDRAM is able to scale to 133 MHz (PC133) up to 180MHz or higher.
DDR (Double Data Rate SDRAM)
DDR basically doubles the rate of data transfer of standard SDRAM by transferring data on the up and down tick of a clock cycle. DDR memory operating at 333MHz actually operates at 166MHz * 2 or 133MHz*2. DDR is a 2.5 volt technology that uses 184 pins in its DIMMs..
Rambus DRAM (RDRAM)
Intel has given RDRAM it's for the consumer market, and it will be the sole choice of memory for Intel's Pentium 4. RDRAM is a serial memory technology.


Memory Speed
SDRAM, at a speed of 66MHz up to 100MHz, and then 133MHz.
DDR comes in P-4 Systems.
Cache :
Cache Memory is fast memory that serves as a buffer between the processor and main memory. The memory structure of PCs is often thought of as just main memory, but it's really a five or six level structure:
The first two levels of memory are contained in the processor itself, consisting of the processor's small internal memory, or registers, and L1 cache, which is the first level of cache, usually contained in the processor.
The third level of memory is the L2 cache, usually contained on the motherboard. The Celeron chip from Intel actually contains 128K of L2 cache within the form factor of the chip.
The fourth level, is being referred to as L3 cache. This cache used to be the L2 cache on the motherboard, but now that some processors include L1 and L2 cache on the chip, it becomes L3 cache. Usually, it runs slower than the processor, but faster than main memory.
The fifth level (or fourth if you have no "L3 cache") of memory is the main memory itself.
The sixth level is a piece of the hard disk used by the Operating System, usually called virtual memory. Most operating systems use this when they run out of main memory, but some use it in other ways as well.
Older memory types
DRAM about 50 MHz.
EDO DRAM about 50 MHz.

WINDOWS SHORT CUT KEYS

F1 --------- See Help on the selected dialog box item
ALT+F4 --------- Quit a program
SHIFT+F10 --------- View the shortcut menu for the selected item
CTRL+ESC --------- Display the Start menu
ALT+TAB --------- Switch to the window you last used or switch to the next
window by pressing ALT while repeatedly pressing TAB.
CTRL+X --------- Cut
CTRL+C --------- Copy
CTRL+V --------- Paste
DEL --------- Delete
CTRL+Z --------- Undo
SHIFT --------- (while inserting the CD-ROM) Bypass AutoPlay when
inserting a compact disc

Video Resolution And Pixel Depth

Adapters Layout

The Monochrome Display Adapter (MDA) is the oldest video adapter board.
MDA boards are for their use of a 25-pin parallel port included with the 9-pin video connector.
The Color Graphics Adapter (CGA) is same as MDA and it is the first graphics adapter to introduce color to PC displays.
A CGA board can be identified by a round RCA-type connector located just above a 9-pin video connector.
The Enhanced Graphics Adapter (EGA) offers more colors and higher display resolution than CGA.
The Video Graphics Array (VGA) board up to 262,144 possible colors for ordinary VGA. VGA connector as a 15-pin high-density connector SVGA (or Super VGA) extends the capabilities of VGA by adding more resolutions and color depths allowing as many as 16 million colors (known as true
color mode) to be displayed at one time.

CPU , Memory, Cache, Chipsets & Bios

CPU: A CPU processing each instruction and virtually all of the data needed by the computer. The type of CPU limits the PC’s overall processing power. Pentium 4, Dual Core, Core 2 Duo, Celeron, Atom, Core i2, Core i3, Core i5 etc.

CPU speed: Even when CPUs are the same, clock speed effects performance. The Speed is 2GHz, 2.4GHz, 2.8GHz , 3.0GHx etc.

Memory slots & Type: Memory is added in the form of SIMMs (Single In-line Memory Modules) or DIMMs (Dual In-line Memory Modules). DDR1, DDR2, or DDR3 etc.
Cache memory: RAM is much slower than a CPU. so slow that the CPU
must insert pauses for memory to catch up. Cache is a technique of improving memory performance.
Chipsets: A chipset is a set of highly optimized, tightly inter-related ICs which, taken together, handle virtually all of the support functions for a motherboard. the Intel chipset, SIS chipset,

BIOS: The BIOS ROM contained on the motherboard capabilities. BIOS is a set of small programs recorded onto ROM ICs that allow the operating system

Inside of the Desktop Computer

ENCLOSURE

The enclosure is the major and main element of a PC.
The enclosure (AT case) forms the mechanical foundation (chassis) of PC. Other sub-assembly is fitted securely to this chassis.
The chassis is electrically grounded through the power supply.
Grounding prevents discharge of static electricity from damaging other sub-assemblies.

POWER SUPPLY
The power supply is located in the rear right quarter of the enclosure.
Ac enters the supply through the ac line cord, which is connected at the rear of the enclosure.
A supply then produces a series of dc outputs that power the motherboard and drives.

MOTHERBOARD
The motherboard (also known as the main board, system board, backplane board, or planar board) holds the majority of a computer’s processing power.
A motherboard contains the system CPU, clock/timing circuits, RAM, cache, BIOS ROM, USB port(s), parallel port, and expansion slots.

CD/DVD Drive bays.
Floppy Drive Bay.
Hard disk Drive (SATA) bays.

How To Open a CPU door (Side Pannel)

Step-1. Switch off the power and dis-connect the power cable.
Step-2. Take the Screedriver (star) and remove the screes and Preserve in a small container.
Step-3. Check the door (side pannel) internal locks. and slowly open with using flat scree drive.
Step-4. Check the Cables (power) and data cards (floppy drive, hard disk drive, cd/dvd drive, etc).
Step-5. Close the door( Side pannel), to check the internal locks and insert.
Step-6. To Fit the screes.
Step-7. Connect the Power cable and swithc on.
Step-8. Swith on the Computer.

Computer Hardware Basics

This article is aimed at introducing you to computer hardware basics, I will stick to the 'basics' for you with high level technical stuff. A typical computer system has 3 basic components:
Keyboard
CPU (central processing unit)
Monitor.
the computer need an input device such as a keyboard. Other devices such as Mouse, barcode reader, joysticks, digital cam, scanner, light pen, etc. also fall into the category of input devices. The monitor is nothing but an output device (or a display device) whose purpose is to display all the information to the user. Computer monitors can be categorized as:
CRT (cathode ray tube) monitors
LCD or LED monitors.
CRT monitors are the box-like monitors that have been around since the last 10-15 years.
LCD and LED monitors are new type. The CPU is the actual 'computer' i.e., it is the component that is responsible for the actual computing that takes place. The CPU consists of the following components:
RAM
Mother Board
Hard disk Drive
Micro Processor
Display card
Sound card
Power Supply and cabinet
USB ports
LAN card
CD/DVD drive
floppy disk drive
cables