Definitions....
Definitions for dummies
Definitions
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CD-ROM- Will play video clips, music CD's, can access information, can assemble and electronic photo book, and can play entire movies. CD-ROM drives have higher capacities than the hard disks that you could purchase in the last few years. For example, when watching a movie, the words may actually be in time with the mouths. CD-ROM stands for Compact Disc-Read Only Memory. However, unlike a CD-RW, you cannot write or re-write to the disk. You can only view what was already on it.
Hard disk- These were invented in the 1950's and started out being 20 inches wide! They were called hard disks only after the floppy disk came out. Before that, they were "Winchesters" or "fixed disks." Actually, hard disks are not that different from cassette tapes. Both can record (save) things and both can go back and erase what has been recorded. However, on a hard disk, you can go back and almost instantly erase one part of it. With a cassette, you would have to go through what could be hours of taping. Hard disks spin up to 170 MPH (272 KPH). Hard disk space ranges from 10 to 40 gigabytes. The seek time is how long it takes the CPU to access that file. Times between 10 and 20 milliseconds are common.
Scanner-There is the digital world and then there is the "real" world with paper and letters. A scanner helps us to have the real world meet the digital world. You could get a flatbed scanner starting around $500 or you could get a lower quality sheet-fed scanners at about $200. Flatbed scanners are the top of the line. You can't get any better than a flatbed. Not to mention that the image is stationary while you are scanning whereas a sheet-fed you would have to put the sheet in and hope that it would go in straight. Flatbeds have better resolution and better color quality. The only problem is that they take up quite a bit of room on your "real" desktop. Sheet-fed, however, will usually run faster than a flatbed. They also will usually take up less space than a flatbed. In fact, you can sometimes get a sheet-fed in your printer. No matter how much you like sheet-fed, you normally can't do color images, books, or magazines. There is another type of scanner, though. A hand-held scanner. These are relatively inexpensive and are only 4 to 5 inches (20-25 cm) wide. These are primarily used for logos and other small pieces of artwork. If you want top of the line, go for the flatbed. If you're short on money, go for the hand-held.
Monitor-This is probably the most important part of the entire computer. Think about it. If you are going to spend 6 or 7 hours a day watching a computer screen, do you want that screen to be a fuzzy one that you have trouble focusing on, or one that has better quality resolution than your $1000 television? The differences between monitors is resolution and color. The resolution is termed in the number columns by the number of rows. So a "640 x 480" has 640 columns and 480 rows. The higher the numbers, the better the resolution, or picture quality. The other factor is colors. The colors can range from 16 colors to millions upon millions of colors. For example, if you have a monitor that can support millions of colors, then what you publish on the Web may look worse to somebody who only has 256 colors. Then there is the factor of dot pitch. Dot pitch is the distance between pixels (tiny dots that make up pictures) on the monitor's screen. A .28 dot pitch has a sharper image than a .31 dot pitch. When buying a monitor, keep in mind that as your sizes increase, so does the price. A 19" monitor could be an extra $200 compared to a 17" monitor. You should also consider getting a MPR II certified monitor. These don't emit as great a magnetic field and let off less radiation.
Floppy Disk- The floppy disk has changed since its debut in 1971. It started out as an 8 inch monster with only one megabyte of memory. Not only that but then, the heads actually touched the tape which means that it will eventually wear down. Then, in 1976, a smaller disk of 5.25 inches came out. It boasted 160 kilobytes of memory and at first could only be used on one side of the disk. However, it was a huge improvement from the first disk. Then, a little later was the entrance of a 360 kilobyte disk where both sides could be saved on. By 1978 the 5.25 inch disk became a double-sided disk carrying as much as 1.2 Megabytes. From there came the IBM 3.5 inch disk in 1984. Even though they only were a double-density disk with 720K, they instantly became a smash hit. However, it only got better with the introduction of a high density 1.44 MEGAbyte disk. This is the most common of disks in use today. But, the reigning champion of all floppy disks is the 3.5 inch Extended Density disk which is produced exclusively from IBM. This "super disk" holds up to a whopping 2.88 MB!
Much like a hard disk, there is a head inside the disk drive that magnetically writes to the disk all of the information that you as a computer user has told it to save. Most computers these days can handle two disk drives without the use of special equipment.
Mice- Although not required, these are some of the most useful tools as far as a computer goes. Mice allow the user to click and drag things around the screen, open and execute program files by double-clicking, and, in the Windows operating system (WOS), a right click enables the user to perform an action on a highlighted object. There are three main types of computer mice. The first is the most popular. It is the mechanical mouse. More likely than not you (yes, you, the one staring at this screen) are using a mechanical mouse. It is the kind with the rolling ball inside.
Here's how it works:
1.) The ball rolls against two rollers set at right angles inside the mouse.
2.) The rollers send the horizontal and vertical positioning information (how far up, down, left, or right to move) back to your computer.
3.) The computer interperates these signals and moves the cursor on the screen. Simple, huh?
There is also a type called optical and yet another called opto-mechanical. In the optical mouse, there isn't a rolling ball, but a beam of light that is bounced off of a reflective pad and back to sensors in the mouse. There are no moving parts, so it is less likely to fail mechanically. With the opto-mechanical mouse, there's a rubber ball to generate movement but it uses photo-interrupter discs to interperate it. These discs are turned by the internal rollers.
What's that? You say you don't have time to hassle with that cord? It 's always in your way? No problem! There are two options to avoid the hassle of a cord. There are infrared mice, which send infrared signals to the computer's mouse port. The only downside is that the mouse must always be within sight of the computer with nothing blocking the beam. Next is the newer radio mice. These use low-power radio signals to transmit positioning information to the computer. These can be several feet away and can even go through walls!
There are also other types of mouse-replaceables. The first, and most popular next to the actual mouse itself, is the trackball. A trackball is basically just a mouse flipped upside down. The user moves the ball with their thumb or finger versus moving the entire mouse. Second is the touch pad. On these, the user moves their finger over a touch-sensitive pad that works almost just like a mouse. Finally come the pen-input devices. An example of this would be a stylus. These are just touch pads with a pen to "write" with.
American Keyboards- Keyboards all have five main sections of keys, the first being function keys. These are the top 10-15 keys labeled with an F. An example would be F1 or F12. Older keyboards have the function keys to the left side of the board. Newer boards have the function keys across the top with a gap between them and the next group of keys, the alphabetical keys. These are the most used keys out of all of them. These have the 26 letters arranged on the keyboard in a pattern based on the frequency of use. Also in this section are the number keys from 1-9 and 0. Then there is the control section containing the Shift keys, Enter/Return, Caps Lock, Alt, Backspace, and Tab keys, and, on Windows keyboards, there is a small flying window that can open the Start Menu. Then there is the numeric keypad on the far right. These can be used by accountants and such who must type many hundreds of numbers without typing a single letter. This pad can also be used for math problems due to its containment of the addition, subtraction, multiplication, and division signs. Finally are the directional keys. These are the four arrow keys and six other directional keys that separate the alphabetical and numerical keys. These keys are primarily used for navigating through documents or web pages and are especially useful for the always unpleasant times when the user's mouse commits suicide and needs overhaul. Most keyboards have a visual similarity to one another but very different feels. For example, some keyboards have a soft, squishy feel to them, as others could have a more responsive feel to them with more resistance and a louder clicking sound to them. There are also more ergonomically designed keyboards that are manufactured to fit to the contours of the hand and wrist. There are also split keyboards with half of the letters on one side and the other half on the other side. These are also more "ergonomically correct" keyboards.
DVD's- DVD stands for Digital Versatile Disk. Basically, a DVD is just a CD- sized disk with anywhere from 4.7 to 17 gigabytes versus the pathetic 650 mb of a CD-ROM.
Fax Machine- The term fax machine is an abbreviation of facsimile machine. A fax machine is just a device that can send photos, reports, résumés, or any other type of document over a phone line.
How it Works:
1.) The fax machine digitizes the image. By this it is meant that the machine divides the image into a grid of dots.
2.) Each dot is programmed electronically using the binary code into a bit mapped image.
3.) Then the rest is easy. The information can be transmitted like normal computer data.
4.) The fax machine on the other side receives the data and interperates the binary back into dots and reprints the picture.
The idea for a fax machine has been around since about 1842 when Alexander Bain invented a machine that was capable of receiving telegraphed messages through the wires and translating them into images on paper. In 1850 F.C. Blakewell patented a machine that did basically the same thing except it was called a copying telegraph. Despite the fact that ideas had been floating around about fax machines, they weren't all that popular until about the mid 1980's. Once they caught on with the general public, they were a smash hit due to the fact that they provided a fast yet simple way of sending information or pictures. There are literally thousands of types or makes of fax machines. There are fax machines that are as big as a person or there are other types that can be included with one's printer/copier/scanner. There are types where the paper feed is automatic and others must be fed manually. Some of the older types keep the paper on a special roll that is then cut to size.
Buffer- The buffer is mainly used in word processors. Basically, it is a type of short term storage. For example, if one was to press all of the keys down at once, a slower computer wouldn't be able to process that much information as quickly as it's been typed, so the computer sends the extra information to the buffer where it is stored until the computer is ready to process it. The buffer is much like a cache in that when it gets full, the computer will begin to beep at the user and everything else typed will be lost.
Bit- A bit is one binary digit, such as a 1 or a 0 (1 is open and 0 is closed.)
Byte- A byte is eight bits or 1 character such as "a". The letter "a" would be (010000010).Each number of binary is a bit.
Nibble- A nibble is four bits or half a byte.
Kilobyte- A kilobyte is 1024 bytes or 8192 bits! The most common abbreviation is KB.
Megabyte- A megabyte is 1,000,000 bytes or 8,000,000 bits! The common abbreviation is MB.
Gigabyte- A Gigabyte is 1,000,000,000 bytes or 8,000,000,000 bits! The common abbreviation is GB.
Terabyte- A Terabyte is 1,000,000,000,000 bytes or 8,000,000,000,000 bits! The common abbreviation is TB.
ROM- Read Only Memory (ROM)- Memory that can only be read. You cannot change the memory on it. CD-ROM's are ROM. They can't be changed. CDRW's are not ROMs because you can burn to them.
RAM- Random Acces Memory (RAM)- RAM is basically like a desk. The bigger the desk the more you can hold on it. It's the same on the computer, less RAM (desk) less you can use (at one time) on the computer. More RAM (desk space) more you can use (at one time) on the computer
Hardware- Hardware is a piece of equipment or a peripheral that can't be changed. It is a hard copy. Like a PC unit. Most hard copies are heavy.
Software- Software is Systems Software, Application Software, and Programming Language Software. It is like a PC game. Most soft copies are light.
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