USB

The Universal Serial Bus is the past, connecting devices to computers has been a real headache
Printers connected to parallel printer ports, and most computers only came with one. Things like Zip drives, which need a high-speed connection into the computer, would use the parallel port as well, often with limited success and not much speed.
Modems used the serial port, but so did some printers and a variety of odd things like Palm Pilots and digital cameras.
List of USB devices that you can buy today includes:
1. Network connections
2. Scanners
3. Mice
4. Joysticks
5. Printers
6. Webcams
7. Digital cameras
8. Scientific data acquisition devices
9. Modems
10. Telephones
11. Speakers
12. Video phones
13. Storage devices such as Zip drives

Modem

Modem (Modulator and Demodulator) is typically used to send digital data over a phone line. The sending modem converts digital data into analog data, which can be transmitted over telephone lines, and the receiving modem converts the analog data back into digital form. This is used to connect to Internet.
Modems are available in different capacities.
-300 bps - 1960s through 1983 or so
-1200 bps - Gained popularity in 1984 and 1985
-2400 bps
-9600 bps - First appeared in late 1990 and early 1991
-19.2 kilobits per second (Kbps)
-28.8 Kbps
-33.6 Kbps
-56 Kbps - Became the standard in 1998
-ADSL, with theoretical maximum of up to 8 megabits per second (Mbps) Gained popularity in 1999

Enhanced Parallel Port/Extended Capabilities Port

Enhanced Parallel Port (EPP) was created by Intel, Xircom and Zenith in 1991. EPP allows for much more data, 500 kilobytes to 2 megabytes, to be transferred each second. It was targeted specifically for non-printer devices that would attach to the parallel port, particularly storage devices that needed the highest possible transfer rate.
Close on the heels of the introduction of EPP, Microsoft and Hewlett Packard jointly announced a specification called Extended Capabilities Port (ECP) in 1992. While EPP was geared toward other devices, ECP was designed to provide improved speed and functionality for printers in 1994, the IEEE 1284 standard was released. It included the two specifications for parallel port devices, EPP and ECP. In order for them to work, both the operating system and the device must support the required specification. This is seldom a problem today since most computers support SPP, ECP and EPP and will detect which mode needs to be used, depending on the attached device. If you need to manually select a mode, you can do so through the BIOS on most computers.

Standard Parallel Port

The original specification for parallel ports was unidirectional, meaning that data only traveled in one direction for each pin. With the introduction of the PS/2 in 1987, IBM offered a new bidirectional parallel port design. This mode is commonly known as Standard Parallel Port (SPP) and has completely replaced the original design. Bidirectional communication allows each device to receive data as well as transmit it. Many devices use the eight pins (2 through 9) originally designated for data. Using the same eight pins limits communication to half-duplex, meaning that information can only travel in one direction at a time. But pins 18 through 25, originally just used as grounds, can be used as data pins also. This allows for full-duplex (both directions at the same time) ommunication.

Parallel Port Basics

Parallel ports were originally developed by IBM as a way to connect a printer to your PC. When IBM was in the process of designing the PC, the company wanted the computer to work with printers offered by Centronics, a top printer manufacturer at the time. IBM decided not to use the same port interface on the computer that Centronics used on the printer. It has 25-pin connector, a PC sends data to a printer or other device using a parallel port, it sends 8 bits of data (1 byte) at a time. These 8 bits are transmitted parallel to each other, as opposed to the same eight bits being transmitted serially (all in a single row) through a serial port. The standard parallel port is capable of sending 50 to 100 kilobytes of data per second.

How Parallel Ports Work?

If you have a printer connected to your computer, there is a good chance that it uses the parallel port. While USB is becoming increasingly popular, the parallel port is still a commonly used interface for printers. Parallel ports can be used to connect a host of popular computer peripherals:
-Printers
-Scanners
-CD burners
-External hard drives
-Iomega Zip removable drives
-Network adapters
-Tape backup drives

CPU Characteristics Pentium I

Pentium I : It is a 'superscalar’ processor. This class of CPU uses a 'U' & 'V' pipe to move instructions incrementally
Processor Speed(s): 60-200 MHz
PGA : 273
Data Bus : 64 bit is capable of Quad Word or Qword data transfers at a time.
Address Bus : 32 bit
Slot/Socket : Socket 4 or 5
FSB : 50-66 MHz
L1 Cache : 16 KB
L2 Cache : No
Voltage : +5 Vdc This processor consumed large amounts of power, generated a lot of heat required the use of a cooling fan.

Processors and Their Data Bus Widths

Processor ----------------------------Data Bus Width
------------------------------------------------------------------
8088 -------------------------------------8-bit
8086 -------------------------------------16-bit
286 ---------------------------------------16-bit
386SX -----------------------------------16-bit
386DX ---------------------------------- 32-bit
Pentium/AMD-K6---------------------64-bit
Pentium Pro/Celeron/II/III---------64-bit
AMD Duron/Athlon -------------------64-bit
Pentium 4 -------------------------------64-bit
Itanium----------------------------------64-bit
Xeon--------------------------------------64-Bit
Atom-------------------------------------64-Bit
Dula Core ------------------------------64-Bit
Core 2 Duo-----------------------------64-Bit
Core 2 Quad ---------------------------64-Bit
Core 2 Extreme------------------------64-Bit
Core i3-----------------------------------64-Bit
Core i5-----------------------------------64-Bit
Core i7-----------------------------------64-Bit

Windows 7 Disadvantages

-Required High hardware configuration.
-Windows 7 needs RAM capacity of at least 1 GB.
-Windows 7 cannot be easily upgraded from windows XP.
-Driver support is not providing for the old systems and the old motherboard and peripherals.
-Many applications can't to run in windows 7
-A bug in Windows Media Player 12
-Expensive than the previous Microsoft operating systems.

Windows Vista Disadvantages

-Requirements high Configurain
-Operating System Cost is High
-Replace the old Hardware, Because the Drivers compatibility
-Change The windows Background. It differ from other os

Windows XP Disadvantages

-Product activation Problem.
-Prone to crashes and hence unstable.
-OS requires significant system resources.
-Parallel port not recognized.
-Susceptable to virus, hacking & other security Problems.
-Retail pricing is high.
-Old peripherals not widely supported.
-Difficult to administer.
-Many flaws and bugs are present in it.
-Older DOS programs may not run on this version.
-No file encryption facility in XP home edition.

Windows 7 of Advantages

- Windows 7 is faster than its previous Versions.
- Calculator has modified with Standard, Scientific, Programmers, and Static with new features like unit conversion, calculations like fuel economy and auto lease payment.
- WordPad in Windows 7 has improved. It can be used to open, edit file names with docx extension. Word prediction is the new feature in Word Pad. Realistic brush has been added in Paint.
- It also supports advanced touch and handwriting recognition.
- Windows 7 supports Virtual Hard Disks with the support of enhanced performances of multi core processors.
- Windows 7 allows the different vendors graphic cards.
- it also allows the user to overcome the clutter in the desktop by introducing three new features Aero Peek, Aero shake and snap.
- Networking has been made much easier than its previous operating systems.
- Windows Media Player 12 has got much enhanced features, drag and drop option.

Windows Vista Advantages

-New Appearance of windows
Desktop, startbutton, start menu, taskbar etc.
-High Level Security for net
-New Media players
-Searching Feature
-Differnt time Format Set and Show
-Parental controls Games etc from Childerns

Advantages of Windows XP

-Hardware support without drivers
-Restore and Rollback
-Better GUI features the previous versions
-Wi-Fi & Wireless LAN Supporting
-Support plug and play
-Headless Systems
-High Security
-Hibernate Once Resume Many
-User friendly OS
-Multiple and Remote Boot Options

Windows Server 2008

1. Server Core Installation
Server Core installations provide a minimal environment for specific roles.
-Active Directory Domain Services
-DNS/DHCP
-File and Print Server
-IIS

2. Hyper-V
Microsoft loves talking about Hyper-V, the virtualization technology built into Windows Server 2008. Hyper-V provides a layer between the hardware and the operating system which allows virtual machines the ability to communicate directly with the hardware, bypassing the host operating system and increasing performance.

3. Terminal Services
Microsoft has 3 new Terminal Services components, RemoteApp, TS WebAccess, and TS Gateway. These concepts will be familiar to any Citrix administrator.

4. Self Healing NTFS
There is a worker thread which runs in the background that corrects the NTFS partition should any problems be found.

5. Support for Hot Swappable Components
Windows Server 2008, while it is up and running, will acknowledge any hardware changes when hot swapping components.

6. Network Access Protection (NAP)
NAP keeps non-compliant computers off your network. NAP can monitor specific computer settings to enforce your workstation compliance standards.

7. Others
Windows Server 2008 includes IIS 7.0 which is a new build that is more capable of delivering streaming media, ASP, and PHP content and applications. It also has an updated management tool which allows you to manage multiple IIS servers from a single MMC.

Windows 2003 Workstation

-Easy to Deploy, Manage, and Use.
-Secure Connected Infrastructure.
-Enterprise-Class Reliability, Availability, Scalability, and Performance.
-Lower TCO Through Consolidation and the Latest Technology.
-Create Dynamic Intranet and Internet Web Sites.
-Support for IPv6. Ping and Tracert have extra IPv6 options.
-Fast Development with Integrated Application Server.
-Work Smarter By Turning Your File Server Into a Powerful Collaboration Server.
-Automate Operations with Script-based and Policy-based Management Tools.
-Increase Document Protection and Availability via Intelligent File Storage.
-Easy to Find, Share, and Reuse XML Web Services
-IPSec Nat Traversal – NAT-T – allows IPSec VPN clients and servers to pass through NAT firewalls.

Windows 2003 Server

-File Server
-Print Server
-Web Server
-Backup Server
-Remote Access
-Fax Server
-Database Server
-Mail Server
-Internet Server
-Proxy Server
-Clustering Service

Windows 2000 Server

1. Windows 2000 is more robust and reliable than Windows NT .
2. CHKDSK works much faster with Windows 2000 than with Windows NT.
3. Windows 2000 clusters are more reliable than Windows NT clusters.
4. The method that Windows NT uses to manage disk volumes makes it difficult to share volumes between different operating systems.
5. Overall, Windows 2000 offers advantages for disk volume management compared to Windows NT.
6. Using the Distributed File System (DFS) to virtualize disk space works poorly in Windows NT. It works better and is supported in Windows 2000.

-The new Virtual Disk Service (VDS)
-Volume Shadow Copy Service (VSS)
-Multipath I/O (MPIO)
-Boot from SAN
-The volume-mounting function
-The Check Disk command,
-The Distributed File System(DFS)
-The Encrypting File System (EFS),

WINDOWS CE

Windows CE is designed to an operating system for a range of communications, entertainment, and mobile-computing devices. It also enables new types of dnon-PC evices that can communicate with each other, share information with Windows-based PCs, and connect to the Internet. It is important that Windows CE is released as an OEM product, and cannot be purchased through retail channels.

-Companion applications.
-Internet Explorer.
-Windows development environment.
-Communication with Windows-based PCs.

WINDOWS NT

WINDOWS NT (WORKSTATION)
Windows NT represents Microsoft’s business communication and networking Operating System. Windows NT similar to Windows 95. Windows NT is a powerful suite of networking and Internet-related features back up, security, cryptography, and system policies configurations. Windows NT also “DOS-mode” supports.

-Management and
-Windows NT Explorer
-Setup manager
-Task Manager
-Internet Explorer
-Hardware profiles
-Multimedia APIs
-Peer Web Services
-Client Support for PPTP
-WINS and DNS integration
-Client support for NDS
-Dial-Up Networking multilink channel aggregation
-Windows messaging client
-System policies and user profiles
-Dial-Up Networking
-Telephony APIs
-Cryptography APIs
-Distributed COM

WINDOWS 98

Windows 98 a full 32-bit operating system. New wizards, utilities, and resources to keep systems running smoothly. Performance is faster for common tasks such as application loading, system startup, and shut down.

Feature of MS Windows 98

-System File Checker.
-Disk Defragmenter Optimization wizard.
-Windows 98 Help Desk.
-Windows System Update.
-Support for Intel MMX processors.
-Power-management improvements.
-Multiple display support.
-Dial-Up Networking improvements.
-Support for Point-to-Point Tunneling Protocol (PPTP).
-Backup utility.
-Faster shutdown.
-Broadcast architecture.
-Support for new hardware.
-Display configuration enhancements.
-System Troubleshooter.
-ActiveMovie.
-Remote Access Server.
-PCMCIA enhancements.
-Support for Infrared Data Association (IrDA) 3.0.
-Distributed Component Object Model (DCOM).
-Support for NetWare Directory Services (NDS).
-Dr. Watson utility.

Microsoft Disk operating system.

MSDOS stands for Microsoft Disk operating system.
MS-DOS is a non-graphical command line 16-bit operating system.
MSDOS created for IBM compatible computers that were first introduced by Microsoft in August 1981.
Last updated in 1994 when MS-DOS 6.22 was released.
The command shell more commonly known as the Windows command line is still used.
MS-DOS does not use a mouse

The command interpreter is integrated in the file COMMAND.com with the internal commands for MS-DOS. The file IO.sys for simple device routines like the access to the monitor, keyboard, fixed storage disks and interfaces. The and MSDOS.sys for the booting code these form the base operating system.

MS-DOS 5.0 use of the High Memory and Upper Memory Area, TSR programs and drivers. The most new external commands in this version are DOSKEY, DOSSHELL, EDIT, EMM386 and LOADHIGH. UNDELETE can recover deleted files, UNFORMAT can undo the format of floppy disks. 2.88 mb floppy disk drives from IBM are now supported.

MSDOS Internal commands

del, erase/delete, rd/rmdir, dir, cd/chdir, cls, md/mkdir, copy, ren/rename, type, set, ver, vol,

MSDOS External commands

attrib, chkdsk, format, fdisk, deltree, diskcopy, diskcomp, edit, doskey, defragment, move, mem, tree, etc.


System environment
- minimum: 512 KB RAM, 5 MB harddisk storage (depends on version for full installation)
- FAT file system
- executable with every x86 compatible CPU
- low RAM and fixed storage disk needs

SYSTEM REQUIREMENTS of OS

FEATURE -------DOS--------WINDOWS 95
----------------------------------------------------------------------------------------
PC platform---------any----------486/25MHz
RAM ----------------640KB--------8MB
Install drive-------1.44MB-------CD-ROM
Hard drive----------6MB----------40–45MB
Display-------------Mono text----VGA
Mouse---------------optional-----Required
----------------------------------------------------------------------------------------

WINDOWS NT
PC platform--------486-25MHz/Alpha/MIPS/R4X00/PowerPC
RAM ---------------16–32MB
Install drive------CDROM
Hard drive---------110MB
Display------------VGA
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS 98 /p>
PC platform------- 486DX 66MHz (Pentium Recommended)
RAM 16MB------- (32MB Recommended)
Install drive----- CD-ROM
Hard drive----- 195MB
Display -----------VGA or higher resolution (16-bit or 24-bit color SVGA recommended).
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS ME
PC platform-------Pentium 150MHz or Above
RAM -------32MB
Install drive------- CD-ROM
Hard drive------- 320MB (2GB)
Display------- VGA or higher resolution (16-bit or 24-bit color SVGA recommended).
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS 2000
PC platform------- Pentium 133MHz or Above
RAM -------------- 64MB
Install drive----- CD-ROM
Hard drive ------- 650MB (2GB)
Display ---------- VGA or higher resolution (16-bit or 24-bit color SVGA recommended).
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS XP
PC platform------- Pentium 300MHz or Above
RAM -------------- 128MB
Install drive----- CD-ROM/DVDROM
Hard drive-------- 2GB
Display ---------- VGA or higher resolution (800x600) (16-bit or 24-bit color SVGA recommended).
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS 2003
PC platform------- Pentium 133MHz or (733MHz recommended)
RAM -------------- 128MB (512MB) Maximum 4GB
Install drive----- CD-ROM/DVD
Hard drive-------- 2GB
Display----------- VGA or higher resolution (800x600) (16-bit or 24-bit color SVGA recommended).
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS Vista
PC platform------- Pentium 800MHz 32bit(x86)/64bit(x64)
RAM--------------- 512MB
Install drive----- DVD Drive
Hard drive-------- 20GB
Display ---------- DirectX 9-class graphics card
Mouse--------------Required

----------------------------------------------------------------------------------------

WINDOWS 7
PC platform------- Pentium 1GHz 32bit(x86)/64bit(x64)
RAM--------------- 1GB
Install drive----- DVD Drive
Hard drive-------- 20GB
Display----------- DirectX 9-class graphics card
Mouse--------------Required

Popular Operating Systems

OPERATING

SYSTEM                PURPOSE

AROS ------------- replacement for Amiga OS

BeOS ------------- Mac/Pentium/Alpha OS

CHORUS ----------- for communication devices

Coherent UNIX ---- UNIX variant

CP/M ------------- precursor to DOS comp.os.cpm

CTOS ------------- networking OS

DR-DOS v6.0 ------ DOS from Novell

FreeBSD ---------- free UNIX variant

GEOS OS ---------- from GeoWorks

GNU -------------- free UNIX variant

Grasshopper OS --- for persistent systems

Helios ----------- real-time embedded OS

HP/UX 10.x ------- a Unix variant from HP

IBM OS/2 v4.x ---- commercial GUI OS

Linux ------------ free UNIX variant

LynxOS ----------- real-time OS

Mach 4.x --------- small multi-processor OS

Macintosh OS8 ---- OS for Macintosh systems

MaxMinix --------- Minix variant for Mac

Magic Cap -------- communication-based OS

Minix small ------ free UNIX variant

MkLinux ---------- Mach-based Linux

MS-DOS v6--------- commercial DOS

Multics ---------- time-sharing OS

NetBSD 1.2 ------- free UNIV variant

Netware v4.x ----- networking OS

NeXTStep --------- networking OS

Novell-DOS v7.0--- DOS version

OSF/1 DEC OS ----- for Alpha

PC-DOS v7.0 ------ DOS version from IBM

Rhapsody --------- Macintosh OS

SCO Unix --------- a UNIX variant from SCO

Solaris 2.5 ------ a UNIX variant from Sun

Unix ------------- the classic workstation OS

UnixWare --------- a UNIX variant from SCO

VMS (OpenVMS)----- the classic mainframe OS

Windows 95 ------- commercial GUI PS OS

Windows 98 ------- commercial GUI PC OS

Windows 2000 ----- commercial networking

Windows 2003 ----- commercial networking

Windows ME ------- commercial GUI PC OS

Windows XP ------- commercial GUI PC OS

Windows Vista ---- commercial GUI PC OS

Windows 7 -------- commercial GUI PC OS

Windows CE ------- version for hand-held PCs

Windows NT v4.0 -- commercial networking

X Window System -- a UNIX variant

Xinu ------------ multi-tasking OS

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

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