Communication Bus :-System uses a number of busses, which are collection

of wires that transmit binary numbers, one bit per wire. A bus is a system that transfers data between computer components or between computers.

Address Bus :- The address bus carries memory addresses. It

has one wire for each bit, therefore 16 bits=16 wires. The memory address carried by this bus alerts memory to open the designated box. Data can then be put in or taken out from there. Address bus is unidirectional.

Data Bus :- Data bus carries data, in binary form,

between the processor and other external units. Its typical size is 8 or 16 bits. The data bus consists of 8 wires, i.e. 256 combinations of binary digits. Data bus is bi-directional.

Control Bus :- Control bus consists of various lines which

have specific functions for coordinating and controlling operations. This system of bus carries the signals that give the report about the status of a device. For ex one wire of bus indicates whether the CPU is currently reading or writing from the main memory. Control bus carries control signal partly unidirectional and partly bi-directional.

Communication Ports

A communication port is mounted in a slot on the computer for easy plugging/unplugging of a peripheral device.

Serial Port :-

Through this port the information travels in and out one bit at a time.

Disadvantage is that it takes 8 times longer to transmit a byte.

Serial ports come in the form of 9-pin or 25-pin male connector.

These ports are often known as communication (COM) port or (RS232C). Mouse, modem etc. are connected using serial port though now mostly they are been replaced by USB port.

Serial Port Socket

Parallel Port :-

can send or receive a byte at a time. Parallel ports come in the form of 25-pin female connector. These ports are used to connect printer, scanner etc.

Parallel Port Socket

RJ 45 Port :- This port is used for Ethernet connections

and can be used between computer and Any networked device, such as a cable modem or a network hub. It is a 8 wire connector.

RJ-45 Connector

RJ 11 Port :-

This port is for connecting to a telephone line. It has six- wire conductors in it and is smaller than RJ45.

RJ-11 Connector

USB Port :- To spare the user botheration of 8 pin,25 pin male, female connectors, the USB has been designed. It gives you s single, standardized, easy to use way to connect a variety of devices to a computer.

used to connect to graphic card that provides high speed video performance typically required to games and other multimedia application.

IR Port- Which sends and receives infrared signals from other devices.It is a wireless data communication. Use radio transmission to transmit a data over a short distance.IR is the same technology used to control a TV set with a remote control. used in laptop computers, PDAs, digital camera, mobile, pagers. It is sensitive to fog and other atmospheric conditions.

AGP Ports :-

Bluetooth describes how mobile phones, computers and PDAs can be easily interconnected using a short range wireless connection. Bluetooth requires that a low cost transceiver chip in each device. Used frequency band of 2.45 GHz that is available globally.

Network Ports :- NP is an address (16 bit address) within a computer, usually associated with a particular protocol. Well known ports 21-FTP, 25 SMTP,80-HTTP,23 Telnet.When computers are connected via networks, they send and receive data and information via network ports. NP used to enable communication b/w programs,application

Bluetooth :-

port that allows connecting telephone equipment with the computer’s card. It simulates analog telephone line digitallyAudio conferences.

Memory Cards:- Is a small storage medium used to store data such as text, pictures, audio, and video etc. Mainly used with digital cameras, computers, mobile phones, music players, video game console etc.

Phone Port :-

SMC are removable flash memory cards that can be used in several different types of digital devices, including digital cameras, mobile phones and digital voice recorders. SMC is the thinner than a credit card. SMC data format is based on the ATA and DOS file standard

Extreme Digital Cards:- able to read and write data faster than any other storage media and yet more economical with battery power.

Smart Media card :-

MMC is weighing less than two grams and smaller than a postage stamp.MMC are suitable for portable devices like digital audio players, digital cameras and PDAs.Card comes in various forms RS-MMC MMC Mobile MMC Micro

SD Card:- Second gen. MMC.Digital card is a highly secure and reliable small flash memory card with a mechanical write protection switch.High storage capacity.High transfer rate for fast copy/download.Non Volatile solid state.

MMC :-

SD Card:- SD cards come in following varieties. MiniMicroSDHC

It is used every where from digital cameras to MP3 players to embedded systems.

Memory stick :- This memory card with thin design is ideal for use in small digital AV electronic products, such as camcorders, and digital still cameras. Memory sticks are high capacity and high performance MC

Compact Flash Cards :-

3) CD-ROM stands forA. Compactable Read Only MemoryB. Compact Data Read Only MemoryC. Compactable Disk Read Only MemoryD. Compact Disk Read Only Memory

Multiple Choice Questions1) When the electrical power is disrupted or cut off, data and programs are lost inA. ROMB. hard diskC. RAMD. secondary storage2) Read Only Memory (ROM)i. Is volatileii. Is programmableiii. Is mounted on the mother boardiv. Contains the bootstrap loaderA. i and iiiB. i, ii and ivC. ii, iii and ivD. iii and iv

4) ALU isA. Arithmetic Logic UnitB. Array Logic UnitC. Application Logic UnitD. None of the above5) MICR stands forA. Magnetic Ink Character ReaderB. Magnetic Ink Code ReaderC. Magnetic Ink Cases ReaderD. None of the above6) Which operation is not performed by computerA. InputtingB. ProcessingC. ControllingD. Understanding7) Pick the one that is used for logical operations or comparisons such as less than equal to or greater than.A. Arithmetic and Logic UnitB. Control UnitC. Both of aboveD. None of the above