USB

Universal Serial Bus. It was developed in the year 1994. Initially USB ports are added to a machine using I/O adapters. Slowly the usage of USB started to increase. Now the USB ports are provided as in-built ports. 

Now all the devices are manufactured with USB ports. Most of the devices are built with USB port instead of parallel and serial ports. Some of the devices that uses USB for connection with system unit are:

• Keyboard
• Mouse
• Webcam
• Speaker
• Joystick
• Printer
• Digital Camera
• Hard disk (external)
• Mobile Phones

USB enables the "Plug and Play" feature. That is, the connected device will be automatically recognized and the device driver will be automatically selected and it will be ready to use. USB uses the technology called "Hot Swapping", in which the devices does not need external power supply for working. Upto 127 devices can be connected to a single port (using hubs). 

The mobile phones uses the USB port for charging.The mobile phones uses the USB port for charging.

Versions

•      1.0 & 1.1 - Data transfer rate is 12 Mbps
•      2.0           - Data transfer rate is 480 Mbps.
•      3.0           - Supports data transfer rate upto 4.8 Gbps.

Types of USB Ports

• USB A-TYPE

• USB B-TYPE

• Micro-USB A

• Micro-USB B

• Micro-USB AB

• USB Mini-b

• USB 3.0 A-TYPE

• USB 3.0 B-TYPE

• USB Micro B

Optical Disc

Optical disk is a storage device. Read & Write operations are done using optical (light) signals. Optical disks  came to use after 'Floppies' which was used as storage device. Optical disks contains many advantages over floppies. Some of the advantages are:

• Portable (easy to transport)
• More storage space
• Reusable

Types
      Optical discs are differentiated based on size and some other factors. Some of the types are:

• CD (Compact Disc)

            It was developed by Sony in the year 1976. The maximum size a CD is 700 MB. This uses Compact Disk File Format (CDFS) filesystem. The various types of CD are: CD-R (CD Recordable), CD-ROM (CD Read Only Memory), CD-RW (CD Rewritable).

          

• DVD (Digital Versatile Disc)

                  It was developed by Philips, Sony, Toshiba and Panasonic in 1995. DVD's have more storage capacity compared to CD's. The storage capacity is from 4.7 GB to 9.4 GB. This uses Universal Digital Format (UDF) format filesystem. The various types of DVD are: DVD-ROM (Read Only Memory), DVD-R (DVD Recordable), DVD-RW (DVD Rewritable).

• Blu-ray

                It was developed in the year 2000 by Sony and Philips. Blu-ray discs has more storage capacity compared to DVD's. This uses Universal Disk Format (UDF) filesystem. The storage capacity is 25 and 50 GB for single and dual layers respectively. 

           Blu-ray can be used upto 200 GB by using multiple dual layers.

• LaserDisc

             It is the grandfather of the optical storage medium. It was developed in the year 1958 by Philips, MCA and Pioneer. This uses analog signals to record the videos. Its diameter is 30cm, which looks like a huge sized DVD. It can be recorded only once. It can be used for playback only.

• Magneto Optical Disc

                  Magneto optical discs looks like floppy discs. But both are different. Floppies use magnetic signals to read and write. But the magneto optical disk uses optical signals to read and write the data. The size of magneto optical disc exists from 650MB to 9.2GB. These disks are available in SCSI (Small Computer System Interface), IDE (Integrated Drive Electronics), USB (Universal Serial BUS).

• FMD (Fluorescent Multilayer Disc)

                 FMD is different from CD and DVD. CD and DVD uses reflective light to store data's, but FMD uses fluorescent light for storing data. CD's and DVD's have the limitations (upto 2 layers) for storing data's. FMD uses 3D optical data storage principle in which the data's can be stored even in 100 layers. The size of FMD's is from 50GB to TB's(terabytes). The FMD will be a transparent disc.

• DMD (Digital Multilayer Disc)

                  DMD's are based on FMD principles. It is developed by D Data Inc. It can store 22 to 32GB binary data. The storage capacity can potentially support upto 100GB. DMD is also a transparent disc.

• UDO (Ultra Density Optical)

                    UDO's are designed to store the data's (videos) in high definition. The size of UDO's are 30 and 60GB. The types of UDO are: WORM (Write Once Read Many), R/W (Rewritable), Compliant WORM.

• PFD (Professional Disc)

                      PFD was introduced in 2003 by Sony. It is a digital recording optical disc for XDCAM and tapeless camcorder. 23GB data can be stored in a single layer PFD and 50GB data can be stored in a dual-layer PFD. PFD supports both standard definition and high definition. Professional Disc for Data (PDD) is a type of PFD, which is used to store data's. It is mostly used by the enterprises for taking backup's.

• VMD (Versatile Multilayer Disc)

                       VMD is a high capacity red laser optical disc. It was developed to compete with Blue-ray. VMD was developed by New Medium Enterprises. The capacity of each layer in VMD is 5GB. The standard size of VMD is 20GB and the maximum size is 30GB. This disc can be used for storing high definition videos.

• HVD (Holographic Versatile Disc)

                     It was developed between 2004 and 2008. HVD was designed to store data's in terabytes (TB). The principle used here is holography, in which red and green rays are combined as a single ray and used for reading and writing. The reading and writing of different type of information are done by using different rays. 100 and 200GB HVD's were introduced in the year 2007.The maximum size of an HVD is 6TB.

• Tapestry Media

                  Tapestry media is similar to holographic versatile disc (HVD). It was developed by InPhase Technologies. Tapestry holographic media is designed to store upto 300GB data. This is used for storing high definition videos and high-end enterprise applications. 

Keyboard

Keyboard is an input device. It is used to give instructions to the system. The keyboard is used to type the letters and it can be used for performing shortcuts while accessing.

Connector types:

• DIN Connector

• PS/2  Connector

• Serial  Connector

• USB

• Wireless

     

Types:

• XT Keyboard

              XT keyboard are the keyboards used with Fullsize AT and Baby AT motherboards. It has 83 keys. XT keyboard contains "Function keys" from F1 to F10. XT keyboard uses DIN connector.

• AT Keyboard

              AT keyboard was introduced with 84 keys. Later it was developed with 101 keys ( as enhanced). AT keyboard also uses the DIN connector for connecting the keyboard with the system unit.

• Standard Keyboard

                   It is the enhanced version of AT keyboard. Standard keyboard contains some additional function keys like Insert, Delete, Home, End, Page Up, Page Down. The standard keyboard is available with both serial connector and with PS/2 connector.

• Multimedia Keyboard

                          Multimedia keyboard is the modern keyboard. It is manufactured with keys such as E-mail, keys for media player, etc,. It is available with PS/2 and USB connector.

• Ergonomic Keyboard

                    Ergonomic keyboard is designed in a different shape which will be more convenient to the user for typing. It is partitioned into two parts which is for easy to use. Ergonomic keyboard is available with PS/2 and USB connectors.

              

FireWire

FireWire is a serial bus interface developed by Apple in 1995. FiewWire is used for high speed data transfer. Upto 63 firewire devices can be connected to a single connector (using adapter cards). FireWire is used to increase the performance (speed) of the other devices.

The data transfer rate is 400 MB per second. Firewire is similar to USB which allows "Plug and Play". Firewire allows two types of communication: Asynchronous and Isochronous for data transfer. Isochronous a type of communication used where continuous, constant, uninterrupted bandwidth is needed. Security can be provided for the data through firewire. It uses Data Strobe encoding scheme for encoding the data. Direct Memory Access (DMA) is possible with the firewire.

Versions: 

• FireWire 400

• FireWire 800

Devices:

           Many devices can be connected to the firewire. Some of the compatible devices are:

• PCI host controller
• Camcorder
• Digital Camera
• Scanner
• Printer
• Hard disk (external)
• Network cables
• Keyboard
• Mouse
• Other firewire devices

Supported Operating Systems:

• Windows
• Macintosh
• Linux
• NetBSD

Motherboard

Motherboard is the backbone of the computer. It is the component present in the system unit. All the components of the computer are connected to the motherboard.

Motherboard Components:

• Processor socket

                It is the socket (connector) for connecting the processor with the motherboard.

• RAM slot

                It is the slot (connector) for connecting the RAM with the motherboard.

• Adapter slot

                It is the slot (connector) for connecting adapter cards, graphics card and sound cards with the board.

• Port

                  Serial Port

                        Serial port consists of pins. Serial port is used to transfer 1 bit data at a time. 

                  Parallel Port

                       Parallel port consists of holes. The parallel port is used to transfer 8 bits data at a time.

• Drive Interfaces

              The drive interface is the interface (connection) between hard disk with the motherboard.

                     1. PATA - Parallel Advanced Technology Attachment 

           2. SATA - Serial Advanced Technology Attachment

  
        
          3. SCSI - Small Computers System Interface

• North Bridge

                  North bridge is the communication part (or path) between RAM and processor.

• South Bridge

                  South bridge is the communication part between processor with the other components (ports).

• BIOS

                 Basic Input Output System. BIOS is used to provide the basic services for the system. BIOS is the initial program executed (runned) after the system is switched on. BIOS initiates the other system processes.

• CMOS

                  Complementary Metal Oxide Semiconductor. It contains:

1. Boot sequence - Assigning the boot option (booting from Hard disk, CD ROM, etc)
2. BIOS sequence
3. Date & Time settings
4. Display device (monitor) information (i.e., brightness, contrast, color depth)

Types:

• Fullsize Advanced Technology (Fullsize AT)

               Specifically designed for server machines. Only the port for the keyboard is in-built, the remaining ports should be added using adapter cards. It supports only Static RAM (SRAM).

• Baby AT

             Designed for client machines. It is developed by IBM. Only the port for the keyboard is in-built, the remaining ports should be added using adapter cards. It supports only Static RAM (SRAM).

• Advanced Technology Extended (ATX)

             ATX board has all the ports are built-in port except the ethernet port (which is used for connecting to a network). ATX board supports both the client and the server machines. ATX board supports DDR1 RAM and SRAM.

• Low Profile Extended (LPX)

                LPX board supports RISER card, which acts as a daughter board.

• New Low Profile Extended (NLX)

               NLX board supports RISER card, which acts as a daughter board.

• Micro Advanced Technology Extended (MTX)

                All the ports in the MTX board are in-built ports including ethernet port. This is the board which is currently being used. The main advantage of the board is its compact design.

• Balanced Advanced Technology Extended (BTX)

                  BTX board was launched in the year 2009. Only few processors (like i5, i7) are supported by this motherboard.