Introduction to Computer Hardware

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The "central processing unit" or "CPU" is the main component and "heart" of the computer system. It is the metal and plastic cabinet that houses the electronic chips and circuit boards. These chips and boards are essential to the computer's operation and actually control other components of the system, like the monitor. Most people refer to this piece of hardware as the "computer" itself. There is a "motherboard" or main circuit board inside it. Mounted on that board is a "microprocessor chip". This is the "brain" of the computer. Recently, there has been much competition in the manufacturing of these chips. They are manufactured by companies named Intel, and AMD. It has become quite difficult to determine which chip is currently the fastest, since their architecture varies somewhat. Now there are also special chips for desktops and notebook computers. One of the fastest is manufactured by Intel and is called the "Pentium IV". However, the AMD "Athlon 64" is also a very powerful chip. Microprocessor chips used to be measured for speed using a measurement called "megahertz" or MHz. However, newer microprocessors are measured in "gigahertz"(GHz). The original IBM PC operated at approximately 4.77 MHz. Today's computers are capable of speeds as high as 3.0 GHz or higher.

Sometimes it is necessary to save your work so that you may return to it later. The saving of this information is referred to as "storage" of the file. Therefore the devices that store the information are referred to as "storage devices". The technology for storing files has become very involved and offers a wide variety of options. However, the basic technology for storing files is the same.

The information to be stored is usually recorded onto a magnetic surface similar to audio recording tape. The computer sends out electrical impulses that alter the ferrous particles on the surface of the disk. The storage devices are then able to read the electrical impulse back off of the surface of the disk.

One of the oldest types of storage devices is the floppy disk. The floppy disk is named for the original old large disks that used to be used. The newer 3.5 " disks are still floppy disks. (Some people mistakenly refer to these as hard disks.) The floppy disk is enclosed in a hard plastic outer shell. These disks are placed into the floppy disk drive and can store approximately 1.44 megabytes of information. This may sound like a lot of information, but actually, once you start working with graphics or photos, these disks can not hold much information. Sometimes they can not even hold one complex graphic. That is why they may not be included in most newer computer systems. They do come in handy for transferring smaller files from one computer to another. Recently, "Flash Drives" or "Thumb Drives" have begun to take the place of any floppy drives and even CD's. They use a static RAM to store the files and can hold tremendous amounts of memory (some hold over 2 GB's!) They are very fast, since they do not use magnetic storage like old disks did.

A "hard disk drive" is also housed in the central processing unit. The hard disk drive is usually mounted inside the computer and cannot be accessed without removing the case. The capacity of a hard disk drive used to be measured in "megabytes" just like a floppy disk drive. New hard disks store anywhere from forty "gigabytes" to 250 gigabytes or more on newer computers. A gigabyte is 1,000 megabytes (1 billion bytes). Some newer drives are measured in "terabytes". A terabyte is 1,000 GB! The "hard disk" is usually not removable. The hard disk is used to load software programs "permanently" (although they can still be erased if necessary). This allows the user to load programs very quickly since they remain stored on the drive even if the computer is turned off. A new computer being purchased should have as large a hard disk drive as the purchaser can afford! When large graphics files are worked on, programs like "Adobe Photoshop" also use extra space on the hard drive like RAM memory.

Most artists, digital photographers, and graphic designers need a higher capacity disk and drive to store large graphics files. One of the most popular high capacity drives used to be the "zip" drive. This type of drive can store 100 to 250 megabytes on a single 3.5" disk. This allows the user to store the equivalent of approximately 70 to 175 floppy disks. There are many other types of storage drives for saving large files using other technologies. The zip drive was based on magnetic storage and is not used quite as much anymore. The newer "optical storage" technologies are a new type of plastic disk using a laser technology for storage. They are CD and DVD drives.

The term "CD" is short for "compact disc". A plain old "CD drive" is usually a "read - only" drive. The CD disc can hold 650-800 MB of information. Newer CD drives have the ability to record on the CD disc as well. These recordable CD drives are called CD-R or CD-RW drives. One drawback to using standard CD media is that once a file is recorded on it, it can not be erased. Many people are under the miconception that you can only record on a CD once. That is not true! "Multi-session" technology for CD's has been around almost since they were invented. That means you may record on a CD, use it to read files and then decide to record other files on it later. New "re-writable" disks are now available. Although they are slightly more expensive (and much slower for saving files!), they allow the capability of recording, erasing and rewriting information to the disk. Mostly all programs are now supplied on CD discs, or if they are downloaded from the Internet, they are "burned" to CD's. CD's can hold video and high quality stereo sound files.

The newest CD-type drive is called a DVD drive (Digital Video Disk). These discs can hold 4.7 GB of information. This allows an entire movie to fit on a single DVD using software compression. Now many new computers contain recordable DVD drives or DVD-RW. DVD technology has two basic formats for recording which can become confusing to anyone purchasing a new drive. Users should try to get a "dual-format" DVD-RW drive. That type of drive allows either type of DVD disk or technology to be used to fit the proper DVD media. Also, "dual-layer" DVD technology allows the storage of up to 9 GB on a single DVD disc!.

The computer "monitor" looks like a television. Just like a television, some monitors have the capability of showing color images or "monochrome" (one color) images. Monochrome monitors come in black and white, green or amber. They are rarely seen or found anymore. Most computer users now prefer to work on a computer with a color monitor. The most widely used is called a "SVGA" (Super VGA) monitor. Monitors are gauged by how fine a picture element the main picture tube contains. This is called the "resolution" of the monitor. Certain "high resolution". monitors offer up to 1600 x 1280 ppi (pixels per inch). Another important consideration is the "dot pitch". A monitor for graphics work should have a dot pitch of no more than .28. A "non-interlaced" monitor is easier on the eyes. This pertains to the scanning rate of the monitor. It is better for long periods of use. Some new monitors have digital on-screen controls like your TV and others contain stereo speakers too. The latest technology is in "Liquid Crystal Displays" or "LCD" monitors. These are called "flat panel displays". The monitor uses a newer digital technology unlike the old analog CRT technology used in older monitors. Besides being so much thinner, the display is very clear and has the capability to display a larger color palette with increased color depth.

The "keyboard" is the part of the computer that allows the computer user to communicate with the computer. It looks like the keyboard on a typewriter, except it has additional "function keys" and "cursor keys", as well as a "numeric keypad" that is set up like an adding machine. It usually attaches to the CPU with a cord, but there are wireless keyboards as well.

Another way for the user to communicate with the computer is to use a "mouse". This computer component got its name from its shape and the thin cable that attaches to the CPU. This device enables the user to move the "cursor" more easily and quickly around the monitor screen. This was originally the component on the Apple Macintosh computer that the manufacturer claimed made the Apple so easy to use. With the addition of the "Windows" graphical user interface program to the IBM compatible computer, there is little or no difference in the ease of use between the two. The mouse is used extensively on most programs to enter commands and create graphics. Newer notebook computers use a technology called a "touchpad" to move the cursor. They take a little getting used to. Many users attach a mouse and bypass the touchpad.

A "Fax /Modem" card is used for file transfers across phone lines. This also allows the user to access on-line services for information and commercial use. The phone connection allows communication across long distances. It also enables workers to stay at home, and "log on" to the company network. Graphic artists will do more work at home and transfer or send their files to their place of business or to a "service bureau" to have high resolution negatives printed out on large imagesetters. The most exciting area of communication is the tremendous growth of the "Internet". It will become an important aspect of design and advertising in the future.

There are also other types of modems that use high-bandwidth technologies including cable modems and DSL modems. These are usually higher in cost and the subscription service or extra phone lines can get expensive. However, many people feel the increased speed is well worth the price!

A "scanner" is a device that operates like a photocopier. A picture or typed page can be placed on the scanner and the computer reads the copy on the scanner and then displays it on the monitor. Using certain programs, the picture or words can be altered and then printed or saved onto a disk. There may still be some of the small hand-held scanners around that the user holds and rolls over a picture to accomplish the same thing. However, the cost of full page scanners has dropped so dramatically, that there is not much use now for a hand-held scanner! Scanners also allow the user to use special software to "read" typewritten pages and convert the image into words that can be edited on the computer. This can save a lot of time if the user doesn't type too quickly!

A "digitizing tablet" is a device that is used by digital artists and digital imaging technicians. It consists of a flat, "tablet-like" surface with electronic sensors beneath it. It allows the user to move a pen-like device on top of it, instead of the mouse, resulting in a more natural drawing motion. Many of the new graphics software programs also respond to "pressure-sensitive" commands. This means that if you press down harder, you'll get a darker line just like a real marker or pencil!

"Sound cards" and speakers give the computer the capability of playing speech, sound effects, soundtracks, music, etc. This helps with tutorials and other software. The card is placed inside the computer in an available slot. Speakers are plugged into the card. A microphone can also be plugged in to record voice tracks. Some new speaker systems allow the computer to play digitized music as well as the best stereos, with sub-woofers and surround sound as well.

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