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COMPUTER FUNDAMENTALS

	Ø RAM Ø Data Storage devices Ø Input Devices Ø Output Devices Ø Mother Board
		Aswin,I Aswin,K Brindha,K Deepa Lakshmi,M Dhanasekar,G.

Input device:

An input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system (such as a computer).

Many input devices can be classified according to:

• Modality of input (e.g. mechanical motion, audio, visual, etc.)
• The input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)
• The number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for CAD applications)

Pointing devices, which are input devices used to specify a position in space, can further be classified according to:

• Whether the input is direct or indirect. With direct input, the input space coincides with the display space. Touch and light pens involve direct input. Examples involving indirect input include the mouse and trackball.
• Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)

Keyboard:

A 'keyboard' is a human interface device which is represented as a layout of buttons. Traditional keyboards use spring-based buttons, though newer variations employ virtual keys, or even projected keyboards.

Examples of types of keyboards include:

• Computer keyboard
• Keyer
• Chorded keyboard
• LPFK

 

Pointing devices:

A pointing device is any human interface device that allows a user to input spatial data to a computer. In the case of mice and touch screens, this is usually achieved by detecting movement across a physical surface. Analogue devices, such as 3D mice, joysticks, or pointing sticks, function by reporting their angle of deflection

 

Output device:

An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.

In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world.

Examples of output devices:

• Speaker
• Headphones
• Screen (Monitor)
• Printer

SPEAKER:

Computer speakers, or multimedia speakers, are speakers external to a computer that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features such as bass and treble controls.

HEADPHONE:

Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as stereo phones, headsets or, colloquially cans. The in-ear versions are known as earphones or ear buds.

MONITOR:

A monitor or display (sometimes called a visual display unit) is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) thin panel, while older monitors use a cathode ray tube. There are different types of monitor such as flat panel monitor, greyscale monitor, CRT monitor, LCD monitor, and OLED monitor.

PRINTER:

In computing, a printer is a peripheral which produces a text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper or transparencies.There are two types of printer. They are Impact printer and Non impact printer. The difference is impact printer and non impact printer is an impact printer has mechanisms resembling those of a typewriter. The example for impact printer is Dot matrix printer and the example for non impact printer is Laser and Inkjet printer.

RAM:

        Random-access memory (RAM) is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order
An early type of widespread writable random-access memory was the magnetic core memory, developed from 1949 to 1952, and subsequently used in most computers up until the development of the static and dynamic integrated RAM circuits in the late 1960s and early 1970s.

Types of RAM:

a) SRAM:

Static random access memory uses multiple transistors, typically four to six, for each memory cell but doesn't have a capacitor in each cell. It is used primarily for cache.

b) DRAM:

Dynamic random access memory has memory cells with a paired transistor and capacitor requiring constant refreshing.

c) FPM DRAM:

Fast page mode dynamic random access memory was the original form of DRAM. It waits through the entire process of locating a bit of data by column and row and then reading the bit before it starts on the next bit. Maximum transfer rate to L2 cache is approximately 176 MBps.

d) EDO DRAM:

Extended data-out dynamic random access memory does not wait for all of the processing of the first bit before continuing to the next one. As soon as the address of the first bit is located, EDO DRAM begins looking for the next bit. It is about five percent faster than FPM. Maximum transfer rate to L2 cache is approximately 264 MBps.
e) SDRAM:

 Synchronous dynamic random access memory takes advantage of the burst mode concept to greatly improve performance. Maximum transfer rate to L2 cache is approximately 528 MBps.
f) DDR SDRAM:

 Double data rate synchronous dynamic RAM is just like SDRAM except that is has higher bandwidth, meaning greater speed. Maximum transfer rate to L2 cache is approximately 1,064 MBps (for DDR SDRAM 133 MHZ).
g) RDRAM:

 Rambus dynamic random access memory is a radical departure from the previous DRAM architecture. Designed by Rambus, RDRAM uses a Rambus in-line memory module (RIMM), which is similar in size and pin configuration to a standard DIMM.

h) Credit Card Memory:

 Credit card memory is a proprietary self-contained DRAM memory module that plugs into a special slot for use in notebook computers.
i) PCMCIA Memory Card:

 Another self-contained DRAM module for notebooks, cards of this type are not proprietary and should work with any notebook computer whose system bus matches the memory card's configuration.
j) CMOS RAM:

 CMOS RAM is a term for the small amount of memory used by your computer and some other devices to remember things like hard disk settings –
k) VRAM:

 Video RAM, also known as multiport dynamic random access memory (MPDRAM), is a type of RAM used specifically for video adapters or 3-D accelerators.

 Storage Devices:

                    A data storage device is a device for recording information. Recording can be done using virtually any form of energy.
A storage device may hold information, process information, or both. A device that only holds information is a recording medium. Devices that process information may either access a separate portable recording medium or a permanent component to store or retrieve information.

Primary Computer Storage Devices:

Primary storage refers to the computer's memory, which connects directly to the computer's CPU. The computer's memory evolved into what is now known as random access memory (RAM) which is a volatile form of storage. Volatile storage means that you totally lose data when you switch the system off.

Processor cache on the other hand is used by the CPU for reducing the time it takes to access the main memory. It stores data coming from the most frequently used applications of the CPU. During normal operations, the CPU checks the processor cache before checking the main memory, making the processing time faster.

Secondary Computer Storage Devices:

These storage devices are external in nature and non-volatile as compared to primary storage devices. Secondary storage devices do not lose data even when they are turned off. Hence, they are the ideal back-up and data storage devices.

Examples of secondary storage devices include; CD and DVD; flash memory; floppy disks; paper and magnetic tape; RAM disks, also called SSDs; ZIP drives; and punch cards. Since secondary storage devices are not attached to the computer's CPU, it takes a longer time for the CPU to access them.

·      Flash Drives

Also known as thumb drives (because of their size) or USB drives (because of the port they connect to), flash drives are the premiere way to store data in a compact and portable fashion. Flash drives range in data capacity from 64 megabytes of 64 gigabytes.

·      External Hard Drives

External hard drives are exactly like the hard drive on any computer, except they are outside of your computer. They usually connect through a USB port (similar to flash drives), are designed either for desktops or laptops and have a storage capacity of up to 700 gigabytes.

·      Smart Cards

Smart cards are also known as memory cards. The usage and types of smart cards have evolved over the years from primary usage in laptops to cell phones and Personal Digital Assistants (PDA's).

·      Online Storage

Also called 'remote backup', online storage sites allow you to store information on their servers. A list of online storage sites are provided in the 'resources' list.

·      Re-writable CD's

These are devices that look exactly like a CD, except you can store information on them. They are often used .

Tertiary Computer Storage Devices:

This type of computer storage device is not as popular as the other two storage device types. Its main use is for storing data at a very large-scale. This includes optical jukeboxes and tape libraries. Tertiary storage devices require a database to organize the data that are stored in them, and the computer needs to go through the database to access those data.

Motherboard:

1. Mouse & keyboard: 

Keyboard Connectors are two types basically. All PCs have a Key board port connected directly to the motherboard. The oldest, but still quite common type, is a special DIN, and most PCs until recently retained this style connector. The AT-style keyboard connector is quickly disappearing, being replaced by the smaller mini DIN PS/2-style keyboard connector.You can use an AT-style keyboard with a PS/2-style socket (or the other way around) by using a converter. Although the AT connector is unique in PCs, the PS/2-style mini-DIN is also used in more modern PCs for the mouse. Fortunately, most PCs that use the mini-DIN for both the keyboard and mouse clearly mark each mini-DIN socket as to its correct use. Some keyboards have a USB connection, but these are fairly rare compared to the PS/2 connection keyboards.
2. USB (Universal serial bus): 

                USB is the General-purpose connection for PC. You can find USB versions of many different devices, such as mice, keyboards, scanners, cameras, and even printers. A USB connector's distinctive rectangular shape makes it easily recognizable. 

USB has a number of features that makes it particularly popular on PCs. First, USB devices are hot swappable. You can insert or remove them without restarting your system.

3. Parallel port:

Most printers use a special connector called a parallel port. Parallel port carries data on more than one wire, as opposed to the serial port, which uses only one wire. Parallel ports use a 25-pin female DB connector. Parallel ports are directly supported by the motherboard through a direct connection or through a dangle.

4. CPU Chip:

 The central processing unit, also called the microprocessor performs all the calculations that take place inside a pc. CPUs come in Variety of shapes and sizes. Modern CPUs generate a lot of heat and thus require a cooling fan or heat sink. The cooling device (such as a cooling fan) is removable, although some CPU manufactures sell the CPU with a fan permanently attached.

5. RAM slots:

Random-Access Memory (RAM) stores programs and data currently being used by the CPU. RAM is measured in units called bytes. RAM has been packaged in many different ways. The most current package is called a 168-pin DIMM (Dual Inline Memory module).   

6. Floppy controller:

 The floppy drive connects to the computer via a 34-pin ribbon cable, which in turn connects to the motherboard. A floppy controller is one that is used to control the floppy drive.

7. IDE controller:

Industry standards define two common types of hard drives: EIDE and SCSI.  Majority of the PCs use EIDE drives. SCSI drives show up in high end PCs such as network servers or graphical workstations. The EIDE drive connects to the hard drive via a 2-inch-wide, 40-pin ribbon cable, which in turn connects to the motherboard. IDE controller is responsible for controlling the hard drive.

8. PCI slot: 

Intel introduced the Peripheral component interconnect bus protocol.  The PCI bus is used to connect I/O devices (such as NIC or RAID controllers) to the main logic of the computer. PCI bus has replaced the ISA bus.

9. ISA slot:

 (Industry Standard Architecture) It is the standard architecture of the Expansion bus. Motherboard may contain some slots to connect ISA compatible cards.

10. CMOS Battery:

 To provide CMOS with the power when the computer is turned off all motherboards comes with a battery. These batteries mount on the motherboard in one of three ways: the obsolete external battery, the most common onboard battery, and built-in battery.
11. AGP slot:

 If you have a modern motherboard, you will almost certainly notice a single connector that looks like a PCI slot, but is slightly shorter and usually brown. You also probably have a video card inserted into this slot. This is an Advanced Graphics Port (AGP) slot

12. CPU slot:

To install the CPU, just slide it straight down into the slot. Special notches in the slot make it impossible to install them incorrectly. So remember if it does not go easily, it is probably not correct. Be sure to plug in the CPU fan's power.  
13. Power supply plug in: 

The Power supply, as its name implies, provides the necessary electrical power to make the pc operate. The power supply takes standard 110-V AC power and converts into +/-12-Volt, +/-5-Volt, and 3.3-Volt DC power.

The power supply connector has 20-pins, and the connector can go in only one direction.