What is ROM?

ROM is an acronym for Read-Only Memory. It refers to computer memory chips containing permanent or semi-permanent pre-recorded programs. Unlike RAM, ROM is non-volatile. Even after you turn off your computer, the contents of the ROM remains available.
Almost every computer comes with a small amount of ROM containing the boot firmware. This holds just enough information so that the computer can check its hardware and load its operating system into RAM. On a PC, the boot firmware is called the BIOS.
Originally, ROM was literally "read-only". To update the programs in ROM, people had to remove and physically replace their ROM chips. Contemporary versions of ROM allow some limited rewriting (referred to as a flash update, as well as the dynamic side of the ROM, which can be written to by the OS), so you can usually upgrade firmware such as the BIOS by using installation software. Rewritable ROM chips include PROMs (programmable read-only memory), EPROMs (erasable read-only memory), EEPROMs (electrically erasable programmable read-only memory), and a common variation of EEPROMs called "flash memory".
What is RAM?

RAM stands for Random Access Memory. RAM is the place where your computer temporarily stores its operating system, application programs, and current data, so that the computer's processor can reach them quickly and easily. When people refer to your computer's memory, they mostly mean its RAM, and it is volatile. Not volatile in the common term, as it won't catch file or explode. Volatile in this instance means that when you turn off your computer, anything in RAM disappears or is erased.

Desktop computers usually come with 16 or more megabytes of RAM, usually increasing in multiples of 8 megabytes. If you use graphic applications, you probably have 32, 64 or more megabytes of memory. Most personal computers are designed so that you can add more RAM modules up to the limit imposed by the motherboard.

If you add more RAM to your computer, you reduce the number of times your processor must read data from your hard disk (Virtual Memory). This usually allows your computer to work considerably faster.

Again, RAM is volatile. It requires a steady flow of electricity to maintain its contents, so data stored in RAM stays there only as long as your computer is running. As soon as you turn the computer off, you lose everything that was in RAM.

When you turn your computer on again, your computer's boot firmware (called a BIOS on a PC) uses instructions stored semi-permanently in ROM chips to read your operating system and related files from the disk and load them back into RAM. On a Personal Computer, different parts of RAM may be more or less easily accessible to programs.

Do you know the difference between memory and disk storage?

Memory and disk storage both refer to internal storage space in a computer.

When people say "memory," they are referring to storage on memory chips, mostly RAM (random access memory). To refer to storage space on disks, people usually say "disk space" or "storage".

Typically, computers have much less memory than disk space. A typical desktop computer might come with 32 or 64 megabytes (32 or 64 million bytes) of RAM, and a hard disk that can hold 4 to 80 gigabytes (4 to 80 billion bytes).

Virtual memory is disk space that has been designated to act like RAM. On a personal computer, different parts of the available RAM may be more or less easily accessible to programs based upon certain MS-DOS executable files. For more information, see the differences between various kinds of memory?

Computers almost always also contain a small amount of ROM, or read-only memory, containing permanent or semi-permanent firmware instructions for checking hardware and starting up the computer. On a personal computer this is referred to as the BIOS.

What is virtual memory?

Virtual memory is a software method of making a computer appear and act as though it has more RAM (Random Access Memory) than is actually present. By reallocating and using available disk space, the operating system of the machine transparently swaps chunks of data between a hard disk and physical memory.

The advantage of doing this is that larger application programs can be loaded, more applications can be used simultaneously, and the programs have more space to store their data. A drawback of virtual memory is that it slows down system operation and is limited to the amount of disk space that is free on the system. Virtual memory is implemented on most major computer operating systems including Unix, VMS, Macintosh System 7.x, Microsoft Windows, Windows NT, and OS/2.

What is a kilobyte?

Although the smallest unit of data that a computer can deal with is a single binary digit (a bit), computers generally do not deal with data as single bits. Instead, computers originally deal with bits in groups of eight. Each such group is referred to as a byte. The symbol K refers to kilobytes and is commonly used to symbolize thousands. It is often used to represent the number of bytes of storage capacity. One K or kilobyte is actually 1,024 units; therefore, if a computer's main memory is described as providing the capability to store 500 K bytes, it would be able to store 500 X 1,024 bytes (512,000 bytes).

What is a megabyte (MB)?

A megabyte is 1,048,576 (1,024 x 1,024) bytes, not one million bytes as might be expected. This odd number is due to computers using binary (base two) math, instead of a decimal (base ten) system.

One byte is the space necessary to store one ASCII character, 8 bits.

Computer storage and memory is typically measured in megabytes (MB). A medium sized novel contains about 1MB of information.

We count in base 10 by powers of 10:

10^1 = 10
10^2 = 10*10 = 100
10^3 = 10*10*10 = 1000
10^6 = 1,000,000

Computers count by base 2:

2^1 = 2
2^2 = 2*2 = 4
2^3 = 2*2*2 = 8
2^10 = 1024
2^20 = 1,048,576

So, in computer terms:

1 kilobyte (KB) = 1024 bytes
1 megabyte (MB) = 1,048,576 bytes
1 gigabyte (GB) = 1,073,741,824 bytes

What is a bit?

A bit is a binary digit, the smallest increment of data on a machine. A bit can hold only one of two values: 0 or 1.

Because bits are so small, you rarely work with information one bit at a time. Bits are usually assembled into a group of 8 to form a byte. A byte contains enough information to store a character, like "h".

What is a byte?

Byte is an abbreviation for "binary term". A single byte is composed of 8 consecutive bits capable of storing a single character.

Different type of computer mouse. Function of Computer Mouse, Mouses or Mice

And the time finally comes Different type of computer mouse has been invented to put an end to the complicated commands in the old version of operating system.

Since its arrival the mouse has reduced the frequent use of the computer keyboardbut especially has simplified the user to access to various functions.

With this device you can track, drag, select, move files, icons and folders…, draws pictures… navigate all over the applications of your computer.

To facilitate your multiple tasks you can use one of the different types of mice.

The mechanical mouse requires a ball to move the cursor on the screen. To get more efficacies with this type of mice, a flat surface named mouse pads is necessary.

The optomechanical or optical-mechanical mouse is a combination of the optical and the mechanical technologies. It uses a ball but detects the mouse movement optically. It is now the most commonly used with PC.

The optical mouse uses a laser; precisely an optical sensor to help detecting the mouse’s moving. More expensive than the two other types, the optical mouses offer more precision and speed and even can be used on any surface.

To be really useful, the mouse has to be connected to your PC. To transmit data to the computer three types of interfaces can be used:

The RS-232C serial port connects the mouse to the computer through a thin electrical cord using a 9 pin connector.

The PS/2 port do the same as the first interface mentioned but using a 6 pin connector.

The USB interface receives various types of mice through a USB connector. One of these advantages to use the USB mouse is the possibility to plug-and-play (it) in front or in the back of your computer case, when it contains these kinds of port.

One of the most interesting mouse technologies invented is the wireless mouse which relies infrared, radio signals or Bluetooth to communicate with the computer. Using no cord, the wireless mouse contains a transmitter to send information to a receiver itself connected to the computer. The wireless mouse is usable from 2m to 10m of the computer.

The cordless mouse uses the wireless communication technology (via infrared, radio or Bluetooth) to transmit data to the computer. And like the wireless, it doesn’t use any cord.

Other specification to consider about different type of mice is the function of the buttons. Depending on the manufacturer a computer mouse can have 1 to 4 buttons. However the most commonly used is the two mouse buttons of which the primary button is located to the left side of the mouse.

Especially for computer games players, some mice have been built with five or more extensive arrays of buttons which give easily access to various functions.

Finally each of the different type of computer mouses seems more usable with the scroll wheel, very effective with long document pages. As a matter of fact the scroll wheel can be rotated up and down to navigate within a page as the arrows “up and down” buttons on the keyboard.

Sometimes instead of the scroll wheel, a center button or a “rocker” button is designed to the same effects. But they have to be pressed at the top or bottom to achieve the same tasks.

Even though you are using Laptop computer it’s actually easier to navigate with one these different types of computer mouse.

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Main Parts Of A Computer

Processor (CPU) - The part of the computer that handles all processes
and instructions supplied by memory unit (RAM)

Memory (RAM) - Random Accessed Memory. The area of the computer that
holds the instructions (processes) and information system gives it.
When you turn the computer off, everything in RAM disappears.

Read Only Memory (ROM) - A chip or disk that holds information that
cannot be changed. Ex CD-ROM, DVD-ROM

Disk drive - A mechanical device that you use to transfer information
back and forth between the computer's memory and a disk.

Floppy disk (3.5") - A magnetically coated disk on which information
can be stored and retrieved. Capacity is 1.44MB - requires a
Floppy-Drive

Zip disk - A magnetically removable coated disk on which information
can be stored and retrieved. Capacity is 100 or 250MB or more -
requires a zip-drive

Hard disk - A large capacity storage area that offers access to store
and retrieve information, very slow compare to RAM.

Monitor - A screen that displays the information in the computer.

Keyboard - A device used to enter data and issue commands to the
computer.

Printer or Scanner - A devices that help to make hard copies o scan
documents into the computer.

Mouse - A small, hand-held device used to control the pointer on the
screen.

Software - Instructions that tell your computer how to perform a task.
Software is stored on the disks in program files. Software cannot be
seen or touched. There are two main kinds of software:
* application software and
* system software

Application software (program) - Software that does specific task,
such as word processing. (Word, Power Point)

System software - Software that the computer system or OS operating
system.

Firmware - A kind of system software - instructions that are built
into the
computer system on ROM chips.

Operating System (OS) - software that acts as a link between you,
application software (programs), and hardware. (Windows 98, Mac OS 9,
Linux 7.2)

Graphical User Interface (GUI) - A phrase that is commonly used to
describe Microsoft Windows and other OS that use pictures to help you
communicate with the computer.

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Ram & Rom

RAM & ROM

Have you ever heard the terms RAM and ROM? These two terms sound very similar and can easily be confused by beginners. However, understanding what they mean and what they do can help you to remember.

Mother Board

Circuits

The motherboard gets its name because it is like a mother to all of the other circuit boards. Found at the bottom of a desktop case or the side of a tower case, the motherboard is the largest circuit board and has many smaller boards plugged into it. It holds all of the most important parts of the computer.

Parts Inside the CPU

Parts of a computer

If you use a desktop computer, you might already know that there isn't any single part called the "computer." A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software, on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)

The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.

Applies to all editions of Windows Vista.

Compare editions

In this topic

• System unit
• Storage
• Mouse
• Keyboard
• Monitor
• Printer
• Speakers
• Modem

See also

• Introduction to computers
• Using your mouse
• Using your keyboard
• Windows Basics: all topics

Parts of a computer

If you use a desktop computer, you might already know that there isn't any single part called the "computer." A computer is really a system of many parts working together. The physical parts, which you can see and touch, are collectively called hardware. (Software, on the other hand, refers to the instructions, or programs, that tell the hardware what to do.)

The illustration below shows the most common hardware in a desktop computer system. Your system may look a little different, but it probably has most of these parts. A laptop computer has similar parts but combines them into a single notebook-sized package.

Desktop computer system

Let's take a look at each of these parts.

System unit

The system unit is the core of a computer system. Usually it's a rectangular box placed on or underneath your desk. Inside this box are many electronic components that process information. The most important of these components is the central processing unit (CPU), or microprocessor, which acts as the "brain" of your computer. Another component is random access memory (RAM), which temporarily stores information that the CPU uses while the computer is on. The information stored in RAM is erased when the computer is turned off.

Almost every other part of your computer connects to the system unit using cables. The cables plug into specific ports (openings), typically on the back of the system unit. Hardware that is not part of the system unit is sometimes called a peripheral device or device.

System unit

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Storage

Your computer has one or more disk drives—devices that store information on a metal or plastic disk. The disk preserves the information even when your computer is turned off.

Hard disk drive

Your computer's hard disk drive stores information on a hard disk, a rigid platter or stack of platters with a magnetic surface. Because hard disks can hold massive amounts of information, they usually serve as your computer's primary means of storage, holding almost all of your programs and files. The hard disk drive is normally located inside the system unit.

Hard disk drive

CD and DVD drives

Nearly all computers today come equipped with a CD or DVD drive, usually located on the front of the system unit. CD drives use lasers to read (retrieve) data from a CD, and many CD drives can also write (record) data onto CDs. If you have a recordable disk drive, you can store copies of your files on blank CDs. You can also use a CD drive to play music CDs on your computer.

CD

DVD drives can do everything that CD drives can, plus read DVDs. If you have a DVD drive, you can watch movies on your computer. Many DVD drives can record data onto blank DVDs.

Tip

If you have a recordable CD or DVD drive, periodically back up (copy) your important files to CDs or DVDs. That way, if your hard disk ever fails, you won't lose your data.

Floppy disk drive

Floppy disk drives store information on floppy disks, also called floppies or diskettes. Compared to CDs and DVDs, floppy disks can store only a small amount of data. They also retrieve information more slowly and are more prone to damage. For these reasons, floppy disk drives are less popular than they used to be, although some computers still include them.

Floppy disk

Why are floppy disks "floppy"? Even though the outside is made of hard plastic, that's just the sleeve. The disk inside is made of a thin, flexible vinyl material.

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Mouse

A mouse is a small device used to point to and select items on your computer screen. Although mice come in many shapes, the typical mouse does look a bit like an actual mouse. It's small, oblong, and connected to the system unit by a long wire that resembles a tail. Some newer mice are wireless.

Mouse

A mouse usually has two buttons: a primary button (usually the left button) and a secondary button. Many mice also have a wheel between the two buttons, which allows you to scroll smoothly through screens of information.

When you move the mouse with your hand, a pointer on your screen moves in the same direction. (The pointer's appearance might change depending on where it's positioned on your screen.) When you want to select an item, you point to the item and then click (press and release) the primary button. Pointing and clicking with your mouse is the main way to interact with your computer. For more information, see Using your mouse.

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Keyboard

A keyboard is used mainly for typing text into your computer. Like the keyboard on a typewriter, it has keys for letters and numbers, but it also has special keys:

• The function keys, found on the top row, perform different functions depending on where they are used.
• The numeric keypad, located on the right side of most keyboards, allows you to enter numbers quickly.
• The navigation keys, such as the arrow keys, allow you to move your position within a document or webpage.

Keyboard

You can also use your keyboard to perform many of the same tasks you can perform with a mouse. For more information, see Using your keyboard.

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Monitor

A monitor displays information in visual form, using text and graphics. The portion of the monitor that displays the information is called the screen. Like a television screen, a computer screen can show still or moving pictures.

There are two basic types of monitors: CRT (cathode ray tube) monitors and LCD (liquid crystal display) monitors. Both types produce sharp images, but LCD monitors have the advantage of being much thinner and lighter. CRT monitors, however, are generally more affordable.

LCD monitor (left); CRT monitor (right)

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Printer

A printer transfers data from a computer onto paper. You don't need a printer to use your computer, but having one allows you to print e‑mail, cards, invitations, announcements, and other materials. Many people also like being able to print their own photos at home.

The two main types of printers are inkjet printers and laser printers. Inkjet printers are the most popular printers for the home. They can print in black and white or in full color and can produce high-quality photographs when used with special paper. Laser printers are faster and generally better able to handle heavy use.

Inkjet printer (left); laser printer (right)

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Speakers

Speakers are used to play sound. They may be built into the system unit or connected with cables. Speakers allow you to listen to music and hear sound effects from your computer.

Computer speakers

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Modem

To connect your computer to the Internet, you need a modem. A modem is a device that sends and receives computer information over a telephone line or high-speed cable. Modems are sometimes built into the system unit, but higher-speed modems are usually separate components.

Cable modem

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Computer data storage

1 GB of SDRAM mounted in a personal computer. An example of primary storage.

40 GB PATA hard disk drive (HDD); when connected to a computer it serves as secondary storage.

160 GB SDLT tape cartridge, an example of off-line storage. When used within a robotic tape library, it is classified as tertiary storage instead.

Computer data storage, often called storage or memory, refers to computer components Computer data storage, often called storage or memory, refers to computer components and recording media that retain digital data used for computing for some interval of time. Computer data storage provides one of the core functions of the modern computer, that of information retention. It is one of the fundamental components of all modern computers, and coupled with a central processing unit (CPU, a processor), implements the basic computer model used since the 1940s.
In contemporary usage, memory usually refers to a form of semiconductor storage known as random-access memory, typically DRAM (Dynamic-RAM) but memory can refer to other forms of fast but temporary storage. Similarly, storage today more commonly refers to storage devices and their media not directly accessible by the CPU (secondary or tertiary storage) — typically hard disk drives, optical disc drives, and other devices slower than RAM but more permanent.^[1] Historically, memory has been called main memory, real storage or internal memory while storage devices have been referred to as secondary storage, external memory or auxiliary/peripheral storage.
The contemporary distinctions are helpful, because they are also fundamental to the architecture of computers in general. The distinctions also reflect an important and significant technical difference between memory and mass storage devices, which has been blurred by the historical usage of the term storage. Nevertheless, this article uses the traditional nomenclature.

Different Parts of the Computer and Their Function

Different Parts of the Computer and Their Function

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A computer is made up of many different components. Each part has a specific function. Whether you need to replace a part, are thinking about building a computer, or just looking for some additional information, it's important to understand the basic computer parts and what they do.

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Case

A Mid-tower computer case

The case is the part of your computer that holds all the other parts. Some common types of computer cases are: full-tower, mid-tower, mini-tower, and laptop. If you have a desktop computer, you are likely using a mid-tower; if you are using a notebook computer, you have a laptop case.

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Top 5 To Try

• History of Memory RAM
• What Are the Most Important Parts of a Computer?
• Different Parts of a Computer Keyboard
• The Different Parts of a Laptop
• List of External Parts of a Computer

Motherboard

1. 
   A Gigabit brand motherboard
   The motherboard is the part of your computer that wires all of the other parts together. Every component of your computer, from the DVD burner to the CPU, will connect directly into the motherboard. Motherboard specs are typically designed around which processor (CPU) the computer uses. For example, if your computer uses an Intel processor, you will need an Intel compatible motherboard.

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Processor (CPU)

An Intel Processor

The processor, or CPU, of a computer is basically the brains of the computer. The processor is responsible for interpreting every code it receives from the other computer components, and making it usable to your operating system. Some common types of processors are Intel Core 2 Duo and AMD Phenom. A processor's speed will often determine the overall speed of your computer.

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Hard Drive

A Western Digital Hard Drive

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Video Cards (Graphic Cards)

A graphic card is the component of your computer that interprets video signal. These cards are necessary so that you can connect a monitor to your computer. There are many types of graphic cards available: anything from high-end gaming cards to TV tuner cards. Some popular graphic card manufacturers are NVIDIA, ATI, and EVGA.

RAM (Memory)

You may have heard of people upgrading the RAM in their computers. RAM is the part of your computer that is used as instant memory. RAM is always in use. For example, if you run many programs at once, you may want to upgrade your RAM because your computer is using more memory. RAM comes in many different configurations, such as DDR2 and DDR3. The type of motherboard you have will determine your RAM.

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Typical Desktop RAM module

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Optical Drive

The last main part of a computer is the optical drive. An optical drive is many times the drive you would use to burn CDs, DVDs, Blu-Ray discs and more. Optical drives can be either slot loading, or tray loading and come in many different configurations. Optical drives connect directly to the motherboard of the computer.

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function of mouse (computer)

A mouse is used as a computer input device to control the location of a cursor on a video display connected to the computer. Computers are used by more and more people every day for use at home and at the office. Modern desktop computers provide users with user-input mechanisms that are well suited for the applications that run on these computers. The use of a hand operated pointing device for use with a computer and its display has become almost universal. A computer user manipulates a pointing device to change the position of a cursor or other object on a computer display, or to select objects on the display. The physical movement of the pointing device results in a similar movement of the cursor and/or object on the display. Data input devices have been used since the sixties as a graphic user interface (GUI) to allow a user to input certain information into computer systems and to modify or operate on images or information displayed on an output screen attached to the computer system. Examples of input devices are trackballs, joysticks, writing pens, computer mice, and graphic tablets. These input devices translate motion applied to the input device into digital data bits delivered to the computer system and allow an individual to communicate with computers. Most computer systems, as for example general purpose computers such as portable computers and desktop computers, receive input from a user via an input device. Different types of mouse devices have been integrated into laptop or notebook computers, such as: pointing sticks, glide points, and track balls, to provide the user the convenience of travel without the necessity of multiple attachments. For desktop computers, the ubiquitous computer mouse constitutes the large majority of pointing devices. A computer mouse is widely used as a pointing device for a personal computer, for controlling movement of a cursor over the display screen of the computer's monitor. Generally speaking, input/output devices receive input from a user or another source and/or provide output to a user or anther source. Keyboards and computer mice are typically considered input devices because they receive input from a user but provide no output to the user. To a personal computer (PC) user, the mouse is one of the basic devices utilized to input data into the PC, the other being the keyboard.

Mouse is the terminology used in computer science to refer to a pointing device which is slid along a flat surface to create x and y output signals as a result of said movement, the signals causing a cursor on the connected computer screen to move and allows the user to point to objects on the screen. A computer mouse is a handheld device that a user slides over a suitable surface causing the cursor on a computer screen to move in a direction determined by the motion of the device. The mouse is a hand-held device operated on a flat surface which, in cooperation with the necessary computer hardware and software, allows the user to control movement of a cursor or pointer on the display. Computer mice are often referred to as cursor positioning devices or cursor control devices, although mice are utilized to perform many other functions, such as to launch applications, re-size and move windows, drag, open and drop documents, select icons, text, menu items in a pull-down menu, and others. The mouse permits a computer user to position and move a cursor on a computer screen without having to use a keyboard. The mouse and mouse button allow the user to move a cursor or other pointing device to a specific area of the computer screen and depress the one or more buttons to activate specific computer program functions. Typically, cursor location is controlled by movement of the mouse across a surface. The mouse includes a tracking device for measuring the movement of the mouse across the surface. The cursor is controlled by moving a mouse containing a movement sensor across a surface. This movement is relayed to the computer where it is translated into a corresponding movement of the cursor on the display. Depressing or clicking a mouse button, signals the computer to initiate a function. The function is determined by the operating system and application program in use with the computer. The movement of the mouse in an X-Y plane typically actuates a mechanical, optical or electrical device within the mouse which produces X and Y position signals which are conveyed to the computer. The computer typically uses the mouse X and Y position signals to manipulate the display of the computer screen, allowing a user to control a program.
Computer mice can be found in a variety of physical embodiments. Typically a mouse comprises a body that serves as a grip for the user's hand and as a structure for mounting a movement sensing system and two or more mouse buttons for selecting computer functions. A computer mouse is ergonomically designed so that a user's hand fits snugly around the device. The computer mouse may be considered as having a bottom surface which is in contact with a work surface such as a mouse pad when in use, and an upper surface which includes one or more pressure-sensitive switches for controlling computer operations when operated. Computer mice are available with electro-mechanical, opto-mechanical, or optical movement sensing systems. The electro- and opto-mechanical systems typically incorporate a ball arranged for rotation in the body and protruding from the bottom of the mouse into contact with the surface on which the mouse is resting. Movement of the mouse causes the ball to rotate. Electrical or optical transducers in the body convert the motion of the ball into electrical signals proportionate to the extent of movement of the mouse in x and y directions. The motion of the mouse can also be sensed with an optical system. The computer mouse typically is a hand-held device operating on the mouse pad which, in cooperation with the computer hardware and software, permits a computer operator to control the path and movement of a cursor or pointer located on the computer display monitor. The mouse having activation buttons so that the appropriate computer programs can be accessed and activated for operations of the computer. A mouse includes at least two switches, which are typically in the form of buttons. These buttons permit the user to signify to the computer to perform various functions. Typically, the left mouse button is the primary button used to select windows, pull down menus, highlight text, etc. These switching functions are typically used to activate a function or command identified by the cursor location, or they can be set to control certain software features. Other mouse buttons may also be included and used to provide control for other software features such as scrolling or paging. In general, there are at least two basic types of mice: electromechanical and optical. The electromechanical mouse has a rubber or metal ball (trackball) protruding from its underside that can roll in all directions. Typically mechanical sensors within the mouse detect the speed and direction the ball is rolling and moves the screen pointer accordingly. To provide good traction, an electromechanical mouse is generally used with a flat soft-cushioned mouse pad. An optical mouse generates cursor signals corresponding to its movement detected by optical reflection.
Mechanical mice typically have an enclosure houses a rubber, plastic, or metal ball. The enclosure allows the ball to move freely in all directions, and mechanical motion sensors, located in the mouseball enclosure, are used to develop a signal that corresponds to the movement of the ball, which is then sent to the computer to move the cursor on the computer display screen. The movement of the ball generates two-dimensional data input for corresponding cursor control, the results of which are visible on a display device of the computer. The mouse has a mouse ball that is located in an interior ball cavity. The mouse ball is held loosely inside of the interior ball cavity by a removable cover that has an opening with a smaller diameter than the mouse and extends outwardly through the cover opening when the mouse is positioned ball side down. The mouse ball typically has a diameter of about 13/16 inch. A retainer plate formed with a circular hole is fitted removably in the opening in the bottom wall of the mouse body. The diameter of the circular hole in the retainer plate is somewhat smaller than the diameter of the mouse ball, so the mouse ball is held captive in the cavity in the mouse body but protrudes through the hole in the retainer plate. In use, movement of the mouse across a mouse pad or other flat surface causes the mouse ball to roll inside of the interior ball cavity, thereby causing mouse contact rollers inside of the mouse to roll. As the user slides the mouse over the mouse pad, the mouse ball rolls against the movement encoding mechanism, which detects the rolling movement of the mouse ball and generates an electrical pulse signal in response thereto. The movement of the mouse contact rollers is then translated into instructions that ultimately cause a cursor on a connected computer screen to move in response to movement of the mouse ball across the mouse pad. A typical mouse pad is made of a resilient material, such as rubber. The upper surface of the mouse pad, on which the mouse slides, is smooth except for a layer of fabric which is glued to the upper surface of the mouse pad in order to provide frictional engagement with the mouse ball.
In addition to mechanical types of pointing devices like a conventional mouse, optical pointing devices have also been developed. The optical mouse has several advantages such as its precise detection of a movement of user's hand and its smooth movement, compared with a conventional ball mouse, thus its use increasing more and more. An optical mouse utilizes optical sensors to detect movement of the mouse relative to a surface. The optical mouse has no mechanical moving parts, and may be used on almost any flat surface. They respond more quickly and precisely than electromechanical mice, and are growing in popularity. An optical mouse overcomes at least the dust problem by generating the movement signal of the mouse by means of detection of reflection light. Generally, an optical mouse is operated by reflecting light emitted from the main body of the optical mouse from a touching object, thus, enabling the movement of the mouse on the pad to be detected and enabling a cursor on a computer monitor to be moved. An optical mouse optically recognizes its movement on the touching object, converts the recognized value to an electric signal, transmits the electric signal to the computer, and thereby the position of the cursor on the monitor can be recognized. In an optical mouse, a light emitted from a light source 8 is reflected by an operating surface, and the reflected light passes through a lens to be inputted to an image sensor made of semiconductor process. The optical mouse measures a quantity of the light projected to the image sensor and stores a pattern made by comparing a difference between pixels of the image sensor. Then, a movement of the mouse is calculated by comparing a current pattern with a pattern made in a prior sample period. An optical mouse generally features a scrolling and zooming wheel, and two customizable buttons on opposing sides of the scroll wheel. The buttons facilitate internet navigation and other routine tasks. A regular optical mouse comprises two optical transmitter receiver modules arranged at right angles. Each optical transmitter receiver module comprises a photo emitter and a photo receiver. The optical mouse determines its own position relative to the surface by comparing the differences between consecutive images.
Conventionally, a computer mouse is connected to a computer system by a cable for transmitting signal/power therebetween. The physical connection of the mouse to the host computer by the cable undesirably restricts free movement of the mouse and may effect undesirable movement. Further constant bending or twisting of the cable may effect deterioration thereof so as to result in disconnection or improper contact of connectors at opposite ends of the cable. Wireless computer mice have been developed to eliminate the need for a cord, and to make it easier for a user to move the mouse around without having to drag a cord. A cableless mouse that communicates with a computer system by means of electromagnetic signals for data transmission overcomes the problem. The wireless computer mouse is generally energized by battery and communicates through infrared transmission or radio frequency transmission to realize wireless operation. To replace the exhausted battery, the battery is often stored in a battery chamber with battery cover. The wireless mice currently available are either infrared based or RF based transmission systems. Infrared signal transmission mouse devices are subject to operational limitations as well in that they must be aligned in the direction of a signal receiver. Such optical mouse transmits an optical signal using a signal generator located at an end of a mouse body to a signal receiver connected to the computer. The infrared systems are the simplest and least expensive, however, they require a line of sight to the receiver. This can result in inconsistent transmission as the mouse is moved or if other objects block the transmission path. RF systems do not suffer from this problem but are more expensive than infrared systems. Nonetheless, RF wireless mice are increasingly being used for wireless mouse controllers over infrared systems due to their performance advantages.