Memory

Memory - Memory can be very confusing but is usually one of the easiest pieces of hardware to add to your computer. It is common to confuse chip memory with disk storage. An example of the difference between memory and storage would be the difference between a table where the actual work is done (memory) and a filing cabinet where the finished product is stored (disk). To add a bit more confusion, the computer's hard disk can be used as temporary memory when the program needs more than the chips can provide.

Random Access Memory or RAM is the memory that the computer uses to temporarily store the information as it is being processed. The more information being processed the more RAM the computer needs.






One of the first home computers used 64 kilobytes of RAM memory (Commodore 64). Today's modern computers need a minimum of 64 Mb (recommended 128 Mb or more) to run Windows or OS 10 with modern software.

RAM memory chips come in many different sizes and speeds and can usually be expanded. Older computers came with 512 Kb of memory which could be expanded to a maximum of 640 Kb. In most modern computers the memory can be expanded by adding or replacing the memory chips depending on the processor you have and the type of memory your computer uses. Memory chips range in size from 1 Mb to 4 Gb. As computer technology changes the type of memory changes as well making old memory chips obsolete. Check your computer manual to find out what kind of memory your computer uses before purchasing new memory chips.

Cards

Cards - Cards are components added to computers to increase their capability. When adding a peripheral device make sure that your computer has a slot of the type needed by the device.

Sound cards allow computers to produce sound like music and voice. The older sound cards were 8 bit then 16 bit then 32 bit. Though the human ear can't distinguish the fine difference between sounds produced by the more powerful sound card they allow for more complex music and music production.

Colour cards allow computers to produce colour (with a colour monitor of course). The first colour cards were 2 bit which produced 4 colours [CGA]. It was amazing what could be done with those 4 colours. Next came 4 bit allowing for 16 [EGA and VGA ] colours. Then came 16 bit allowing for 1064 colours and then 24 bit which allows for almost 17 million colours and now 32 bit and higher allow monitors to display almost a billion separate colours.

Video cards allow computers to display video and animation. Some video cards allow computers to display television as well as capture frames from video. A video card with a digital video camera allows computers users to produce live video. A high speed connection is required for effective video transmission.

Network cards allow computers to connect together to communicate with each other. Network cards have connections for cable, thin wire or wireless networks. For more information see the section on Networks.

Digital camera

 Digital cameras allow you to take digital photographs. The images are stored on a memory chip or disk that can be transferred to your computer. Some cameras can also capture sound and video.

Case - The case houses the microchips and circuitry that run the computer. Desktop models usually sit under the monitor and tower models beside. They come in many sizes, including desktop, mini, midi, and full tower. There is usually room inside to expand or add components at a later time. By removing the cover off the case you may find plate covered, empty slots that allow you to add cards. There are various types of slots including IDE, ASI, USB, PCI and Firewire slots.

Depending on the type notebook computers may have room to expand . Most Notebooks also have connections or ports that allows expansion or connection to exterior, peripheral devices such as monitor, portable hard-drives or other devices.

Scanner

Scanners- Scanners allow you to transfer pictures and photographs to your computer. A scanner 'scans' the image from the top to the bottom, one line at a time and transfers it to the computer as a series of bits or a bitmap. You can then take that image and use it in a paint program, send it out as a fax or print it. With optional Optical Character Recognition (OCR) software you can convert printed documents such as newspaper articles to text that can be used in your word processor. Most scanners use TWAIN software that makes the scanner accessable by other software applications.


different types of scanners

There are five different types of scanners: flatbed, sheetfed, photo, film, and handheld. The five kinds differ greatly, so choosing the type you need is simply a matter of asking yourself a few questions about how you will primarily use the scanner. Will you usually be scanning text documents? Will you need to scan odd-sized pages? Do you only need it for scanning pictures of the kids to your mother-in-law? Start with these questions, and look at they types below.

Flatbed: The most popular type of scanner, because it comes in a wide range of prices for an equally wide range of uses. Generally, flatbed scanners are best for scanning regular-sized documents or photos. The only possible downside to the versatile flatbed is size: if you are very limited when it comes to desk space, or if you will need to scan legal-size documents or newspaper clippings (flat bed scanners don't always have legal or tabloid settings), a sheetfed scanner may be a better choice.

Sheetfed: A generally inexpensive scanner, but as the prices drop on the faster flatbed scanners, so does the demand for sheetfed models. Sheetfeds are unique in their compact size and ability to accommodate larger, more irregular-sized documents, such as legal papers and newspaper clippings. If you aren't concerned with speed or volume, but your priority is scanning basic text documents that won't fit the confines of a flatbed, this may be the scanner for you.

Photo: For those consumers strictly scanning photographs, a photo scanner may be a good option. Also, if you aren't sure about making the leap from your old 35-mm to a digital camera, photo scanners allow you to stick with your old favorite and still take advantage of high technology. Photo scanners tend to be very compact in size, which is good for those with limited desk space; however, the size of the scanner also limits the size of photographs you are able to scan. (Most photo scanners limit size to 5"x7" photos.)

Film: If you are obsessed with having crisp photographic quality, a film scanner may be what you're looking for. Most film scanners rival digital cameras not only in price (film scanners are less expensive overall) but also in image quality (higher resolution). Because film scanners scan the negative itself rather than the photo, they can scan at outrageously high resolutions, making images cleaner and sharper. The main downside ? you can only scan film or slides, not paper or photos. If you will need to scan more than just film, you may want to consider a flatbed scanner with a transparency attachment that supports 35-mm film and slides. (It may be a more economical choice as well.)

Handheld: As the name implies, handheld scanners are best if you're constantly on the go. While portability is a plus, the downside to most handheld scanners is that they can only scan a few lines at a time, and only in grayscale. Some higher-end handheld scanners include special software that enables the user to straighten out and connect the scanned lines of the document, but for some consumers, this may seem like more of a hassle than a convenience. Akin to the handheld is the business card scanner.

Modems

Modem - A modem is used to translate information transferred through telephone lines, cable, satellite or line-of-sight wireless.

The term stands for modulate and demodulate which changes the signal from digital, which computers use, to analog, which telephones use and then back again. Digital modems transfer digital information directly without changing to analog.

Modems are measured by the speed that the information is transferred. The measuring tool is called the baud rate. Originally modems worked at speeds below 2400 baud but today analog speeds of 56,000 are standard. Cable, wireless or digital subscriber lines can transfer information much faster with rates of 300,000 baud and up.

Modems also use Error Correction which corrects for transmission errors by constantly checking whether the information was received properly or not and Compression which allows for faster data transfer rates. Information is transferred in packets. Each packet is checked for errors and is re-sent if there is an error.

Anyone who has used the Internet has noticed that at times the information travels at different speeds. Depending on the amount of information that is being transferred, the information will arrive at it's destination at different times. The amount of information that can travel through a line is limited. This limit is called bandwidth.

There are many more variables involved in communication technology using computers, much of which is covered in the section on the Internet.

Printers

Printers

 

Printers - The printer takes the information on your screen and transfers it to paper or a hard copy. There are many different types of printers with various levels of quality. The three basic types of printer are; dot matrix, inkjet, and laser.

• Dot matrix printers work like a typewriter transferring ink from a ribbon to paper with a series or 'matrix' of tiny pins.

• Ink jet printers work like dot matrix printers but fires a stream of ink from a cartridge directly onto the paper.

• Laser printers use the same technology as a photocopier using heat to transfer toner onto paper.

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. Many printers are primarily used as local peripherals, and are attached by a printer cable or, in most newer printers, a USB cable to a computer which serves as a document source. Some printers, commonly known as network printers, have built-in network interfaces, typically wireless and/or Ethernet based, and can serve as a hard copy device for any user on the network. Individual printers are often designed to support both local and network connected users at the same time. In addition, a few modern printers can directly interface to electronic media such as memory cards, or to image capture devices such as digital cameras, scanners; some printers are combined with a scanners and/or fax machines in a single unit, and can function as photocopiers. Printers that include non-printing features are sometimes called multifunction printers (MFP), multi-function devices (MFD), or all-in-one (AIO) printers. Most MFPs include printing, scanning, and copying among their features. 


Printing technology

Printers are routinely classified by the technology they employ; numerous such technologies have been developed over the years. The choice of engine has a substantial effect on what jobs a printer is suitable for, as different technologies are capable of different levels of image or text quality, print speed, low cost, noise; in addition, some technologies are inappropriate for certain types of physical media, such as carbon paper or transparencies.

A second aspect of printer technology that is often forgotten is resistance to alteration: liquid ink, such as from an inkjet head or fabric ribbon, becomes absorbed by the paper fibers, so documents printed with liquid ink are more difficult to alter than documents printed with toner or solid inks, which do not penetrate below the paper surface.

Cheques should either be printed with liquid ink or on special cheque paper with toner anchorage. For similar reasons carbon film ribbons for IBM Selectric typewriters bore labels warning against using them to type negotiable instruments such as cheques. The machine-readable lower portion of a cheque, however, must be printed using MICR toner or ink. Banks and other clearing houses employ automation equipment that relies on the magnetic flux from these specially printed characters to function properly.

Mouse

Mouse - Most modern computers today are run using a mouse controlled pointer. Generally if the mouse has two buttons the left one is used to select objects and text and the right one is used to access menus. If the mouse has one button (Mac for instance) it controls all the activity and a mouse with a third button can be used by specific software programs.

One type of mouse has a round ball under the bottom of the mouse that rolls and turns two wheels which control the direction of the pointer on the screen. Another type of mouse uses an optical system to track the movement of the mouse. Laptop computers use touch pads, buttons and other devices to control the pointer. Hand helds use a combination of devices to control the pointer, including touch screens.
 
Note: It is important to clean the mouse periodically, particularly if it becomes sluggish. A ball type mouse has a small circular panel that can be opened, allowing you to remove the ball. Lint can be removed carefully with a tooth pick or tweezers and the ball can be washed with mild detergent. A build up will accumulate on the small wheels in the mouse. Use a small instrument or finger nail to scrape it off taking care not to scratch the wheels. Track balls can be cleaned much like a mouse and touch-pad can be wiped with a clean, damp cloth. An optical mouse can accumulate material from the surface that it is in contact with which can be removed with a finger nail or small instrument.


How mouse system works

Sensors are the movement detectors (typically optomechanical) which sense the mouse movement and button swiches which sense the button states. Mouse controller reads the state of those sensors and takes acount of current mouse position. When this information changes the mouse controller sends a packet of data to the computer data interface controller.
The mouse driver in the computer received that data packet and decodes the information from it and does actions based on the information. Typically mouse driver has the information of the current mouse state (position and button states) and tells them to the application or operating when it asks them. Typically the mouse drive calls mouse cursor moving routines when mouse is moved and sends messages to the software when buttons are pressed.

In typical modern PC mouse driver the actual cursor movement is not linearly related to the mouse movement. This might sound a bit strange but it has been found that there are better ways to change the mouse movement to cursor muvement than just simply causing one mouse step to move the cursor one pixel. During the pioneering research done at Apple Computer in the devellopment of the graphical user interface (GUI), it became apparent that no particular ratio between mouse movement and cursor movement was best suited for all tasks.

Early work detected that there are two basic movements in the use of pointing devices: move cursor to desired area and then exactly to desired target. Those two movements have contradictory requirements, so Apple solved the problem by monitoring the mouse movements and change it's CPI (counts per inch) characteristics. When the mouse was moved slowly it remained 100 CPI and when the mouse was moved fast it appears to be 400 CPI mouse. This method of adjusting CPI based on its usage has now been adopted by the default driver in Windows 95 and is now the most commonly accepted way of translating mouse movements to cursor screen movement

Drives

DVD-Drive

Removable Storage and/or Disk Drives - All disks need a drive to get information off - or read - and put information on the disk - or write. Each drive is designed for a specific type of disk whether it is a CD, DVD, hard disk or floppy. Often the term 'disk' and 'drive' are used to describe the same thing but it helps to understand that the disk is the storage device which contains computer files - or software - and the drive is the mechanism that runs the disk.

Digital flash drives work slightly differently as they use memory cards to store information so there are no moving parts. Digital cameras also use Flash memory cards to store information, in this case photographs. Hand held devices use digital drives and many also use removable or built in memory cards.   

 DVD stands for Digital Versatile/Video Disc, DVDR stands for DVD Recordable and DVDRW for DVD ReWriteable. If you're familiar with regular audio/music CDs or regular DVD-Video discs, then you will know what a recordable DVD looks like. A recordable DVD stores up to 2 hours of very good quality DVD-Video, including several audio tracks in formats like stereo, Dolby Digital or DTS and also advanced menu systems, subtitles and still pictures that can be played by many standalone DVD Players and most computer DVD-ROMs. If you choose to lower the video quality it is possible to store several hours video on a recordable DVD using low bitrates and low resolution with video quality more like VHS, SVHS, SVCD, CVD or VCD. It is also possible to have up to 4.37* GB ordinary data or mix DVD-Video and data on a recordable DVD that can be played by most computer DVD-ROMs.

There are three competing DVD Recording standards, DVD-R/DVD-RW and DVD+R/DVD+RW have pretty similiar features and are compatible with many standalone DVD Players and most DVD-ROMs while DVD-RAM has less DVD Player and DVD-ROM compatibility but better recording features.

DVD-R and DVD-RW
 
DVD-R was the first DVD recording format released that was compatible with standalone DVD Players.
DVD-R is a non-rewriteable format and it is compatible with about 93% of all DVD Players and most DVD-ROMs.
DVD-RW is a rewriteable format and it is compatible with about 80% of all DVD Players and most DVD-ROMs.
DVD-R and DVD-RW supports single side 4.37 computer GB* DVDs(called DVD-5) and double sided 8.75 computer GB* DVDs(called DVD-10).
These formats are supported by DVDForum.

DVD+R and DVD+RW
 
DVD+R is a non-rewritable format and it is compatible with about 89% of all DVD Players and most DVD-ROMs.
DVD+RW is a rewritable format and is compatible with about 79% of all DVD Players and most DVD-ROMs.
DVD+R and DVD+RW supports single side 4.37 computer GB* DVDs(called DVD-5) and double side 8.75 computer GB* DVDs(called DVD-10).
These formats are supported by the DVD+RW Alliance.

DVD+R DL 

DVD+R DL or called DVD+R9 is a Dual Layer writeable DVD+R. The dual layered discs can hold 7.95 computer GB* (called DVD-9) and dual layered double sides 15.9* computer GB (called dvd-18).

DVD-R DL
 
DVD-R DL or called DVD-R9 is a Dual Layer writeable DVD-R. The dual layered discs can hold 7.95 computer GB* (called DVD-9) and dual layered double sides 15.9* computer GB (called dvd-18).

DVD-RAM
 
DVD-RAM has the best recording features but it is not compatible with most DVD-ROM drives and DVD-Video players. Think more of it as a removable hard disk. DVD-RAM is usually used in some DVD Recorders.
This format is supported by DVDForum.

Case

Case - The case houses the microchips and circuitry that run the computer. Desktop models usually sit under the monitor and tower models beside. They come in many sizes, including desktop, mini, midi, and full tower. There is usually room inside to expand or add components at a later time. By removing the cover off the case you may find plate covered, empty slots that allow you to add cards. There are various types of slots including IDE, ASI, USB, PCI and Firewire slots.

Depending on the type notebook computers may have room to expand . Most Notebooks also have connections or ports that allows expansion or connection to exterior, peripheral devices such as monitor, portable hard-drives or other devices.

Monitors

Monitor

Monitors - The monitor shows information on the screen when you type. This is called outputting information. When the computer needs more information it will display a message on the screen, usually through a dialog box. Monitors come in many types and sizes. The resolution of the monitor determines the sharpness of the screen. The resolution can be adjusted to control the screen's display..

Most desktop computers use a monitor with a cathode tube or liquid crystal display. Most notebooks use a liquid crystal display monitor.
To get the full benefit of today's software with full colour graphics and animation, computers need a color monitor with a display or graphics card.

Keyboards

Keyboard

Keyboard - The keyboard is used to type information into the computer or input information. There are many different keyboard layouts and sizes with the most common for Latin based languages being the QWERTY layout (named for the first 6 keys). The standard keyboard has 101 keys. Notebooks have embedded keys accessible by special keys or by pressing key combinations (CTRL or Command and P for example). Ergonomically designed keyboards are designed to make typing easier. Hand held devices have various and different keyboard configurations and touch screens.

Some of the keys have a special use. They are referred to as command keys. The 3 most common are the Control (CTRL), Alternate (Alt) and the Shift keys though there can be more (the Windows key for example or the Command key). Each key on a standard keyboard has one or two characters. Press the key to get the lower character and hold Shift to get the upper.




Basic PC shortcut keys


 Shortcut Keys                                                   Description


Alt + F                                                      File menu options in current program.


Alt + E                                                      Edit options in current program


F1                                                             Universal Help in almost every Windows program.


Ctrl + A                                                     Select all text.


Ctrl + X                                                    Cut selected item.


Shift + Del                                                 Cut selected item.


Ctrl + C                                                    Copy selected item.


Ctrl + Ins                                                   Copy selected item


Ctrl + V                                                     Paste


Shift + Ins                                                  Paste


Home                                                       Goes to beginning of current line.


Ctrl + Home                                             Goes to beginning of document.


End                                                          Goes to end of current line.


Ctrl + End                                                Goes to end of document.


Shift + Home                                            Highlights from current position to beginning of line.


Shift + End                                               Highlights from current position to end of line.


Ctrl + Left arrow                                      Moves one word to the left at a time.


Ctrl + Right arrow                                    Moves one word to the right at a time.

Central Processing Unit

[CPU]-Central Processing Unit

 

 

 

 

 

 

Central Processing Unit - Though the term relates to a specific chip or the processor a CPU's performance is determined by the rest of the computer's circuitry and chips.

Currently the Pentium chip or processor, made by Intel, is the most common CPU though there are many other companies that produce processors for personal computers. Examples are the CPU made by Motorola and AMD.With faster processors the clock speed becomes more important. Compared to some of the first computers which operated at below 30 megahertz (MHz) the Pentium chips began at 75 MHz in the late 1990's. Speeds now exceed 3000+ MHz or 3 gigahertz (GHz) and different chip manufacturers use different measuring standards (check your local computer store for the latest speed). It depends on the circuit board that the chip is housed in, or the motherboard, as to whether you are able to upgrade to a faster chip. The motherboard contains the circuitry and connections that allow the various component to communicate with each other.

Though there were many computers using many different processors previous to this I call the 80286 processor the advent of home computers as these were the processors that made computers available for the average person. Using a processor before the 286 involved learning a proprietary system and software. Most new software are being developed for the newest and fastest processors so it can be difficult to use an older computer system.



The processor (CPU, for Central Processing Unit) is the computer's brain. It allows the processing of numeric data, meaning information entered in binary form, and the execution of instructions stored in memory.


The processor (called CPU, for Central Processing Unit) is an electronic circuit that operates at the speed of an internal clock thanks to a quartz crystal that, when subjected to an electrical currant, send pulses, called "peaks". The clock speed (also called cycle), corresponds to the number of pulses per second, written in Hertz (Hz). Thus, a 200 MHz computer has a clock that sends 200,000,000 pulses per second. Clock frequency is generally a multiple of the system frequency (FSB, Front-Side Bus), meaning a multiple of the motherboard frequency.

With each clock peak, the processor performs an action that corresponds to an instruction or a part thereof. A measure called CPI (Cycles Per Instruction) gives a representation of the average number of clock cycles required for a microprocessor to execute an instruction. A microprocessor’s power can thus be characterized by the number of instructions per second that it is capable of processing. MIPS (millions of instructions per second) is the unit used and corresponds to the processor frequency divided by the CPI.

An instruction is an elementary operation that the processor can accomplish. Instructions are stored in the main memory, waiting to be processed by the processor. An instruction has two fields:
Registers

When the processor executes instructions, data is temporarily stored in small, local memory locations of 8, 16, 32 or 64 bits called registers. Depending on the type of processor, the overall number of registers can vary from about ten to many hundreds.

Introduction to Computer Hardware

The Hardware Are The Part Of The Computer 

1. Central Processing Unit (CPU)
2. Keyboards
3. Monitors
4. Case
5. Drives
6. Mouse
7. Printers
8. Modems
9. Scanners
10. Digital cameras
11. Cards[ sound, colour, video]
12. Memory