Tuesday, September 28, 2010
Stands for the "Institute of Electrical and Electronics Engineers." This is a non-profit organization that develops, defines, and reviews electronics and computer science standards. Though it is a U.S. based organization, standards developed by the IEEE often become International standards. Some examples of commonly-used products standardized by the organization are the IEEE 1284 interface (a.k.a. Parallel Port), which many printers use, and the IEEE 1394 interface (a.k.a. Firewire), which is a super-fast connection for digital video cameras, hard drives, and other peripherals.
The IEEE describes itself as "the world's largest technical professional society -- promoting the development and application of electrotechnology and allied sciences for the benefit of humanity, the advancement of the profession, and the well-being of our members." Perhaps they could standardize a more simplified definition of their organization.
Stands for "Dots Per Inch." DPI is used to measure the resolution of an image both on screen and in print. As the name suggests, the DPI measures how many dots fit into a linear inch. Therefore, the higher the DPI, the more detail can be shown in an image.
It should be noted that DPI is not dots per square inch. Since a 600 dpi printer can print 600 dots both horizontally and vertically per inch, it actually prints 360,000 (600 x 600) dots per square inch.
Also, since most monitors have a native resolution of 72 or 96 pixels per inch, they cannot display a 300 dpi image in actual size. Instead, when viewed at 100%, the image will look much larger than the print version because the pixels on the screen take up more space than the dots on the paper.
Monday, September 27, 2010
In the computing world, the term "wireless" can be rather ambiguous, since it may refer to several different wireless technologies. The two most common types of wireless capabilities computers have are Wi-Fi and Bluetooth.
Wi-Fi is the technology used for wireless networking. If your computer has a wireless card, it is most likely Wi-Fi compatible. The wireless card transmits to a wireless router, which is also based on the Wi-Fi standard. Wireless routers are often connected to a network, cable modem, or DSL modem, which provides Internet access to anyone connected to the wireless network.
Bluetooth is the technology often used for wireless keyboards and mice, wireless printing, and wireless cell phone headsets. In order to use a device such as a Bluetooth keyboard or mouse, your computer must be Bluetooth-enabled or have a Bluetooth adapter installed.
Computers may also use other wireless technologies aside from Wi-Fi and Bluetooth. Products such as remote controls and wireless mice may use infrared or other proprietary wireless technologies. Because of the many wireless options available, it is a good idea to check the system requirements of any wireless device you are considering buying.
Memory is hardware that your computer uses to load the operating system and run programs. It consists of one or more RAM chips that each have several memory modules. The amount of real memory in a computer is limited to the amount of RAM installed. Common memory sizes are 256MB, 512MB, and 1GB.
Because your computer has a finite amount of RAM, it is possible to run out of memory when too many programs are running at one time. This is where virtual memory comes in. Virtual memory increases the available memory your computer has by enlarging the "address space," or places in memory where data can be stored. It does this by using hard disk space for additional memory allocation. However, since the hard drive is much slower than the RAM, data stored in virtual memory must be mapped back to real memory in order to be used.
The process of mapping data back and forth between the hard drive and the RAM takes longer than accessing it directly from the memory. This means that the more virtual memory is used, the more it will slow your computer down. While virtual memory enables your computer to run more programs than it could otherwise, it is best to have as much physical memory as possible. This allows your computer to run most programs directly from the RAM, avoiding the need to use virtual memory. Having more RAM means your computer works less, making it a faster, happier machine.
Troubleshooting is the process of diagnosing the source of a problem. It is used to fix problems with hardware, software, and many other products. The basic theory of troubleshooting is that you start with the most general (and often most obvious) possible problems, and then narrow it down to more specific issues.
Many product manuals have a "Troubleshooting" section in the back of the manual. This section contains a list of potential problems, which are often phrased in the form of a question. For example, if your your computer's monitor is not producing an image, you may be asked to answer the following troubleshooting questions:
Is the monitor plugged in to a power source?
Is the monitor turned on?
Is the monitor cable plugged into the computer?
Is the computer turned on?
Is the computer awake from sleep mode?
If the answers to all the above questions are Yes, there may be some additional questions such as:
Does your computer have a supporting video card?
Have you installed the necessary video card drivers?
Is the monitor resolution set properly?
Typically, each of these questions will be followed by specific advise, whether the answer is Yes or No. Sometimes, this advice is presented as a flowchart diagram. This means each question is followed by a series of other questions, depending on the answer. However, in many cases, only single solutions are provided for each question.
Troubleshooting is something we all have to do at some point, though some of us have to troubleshoot product problems more often than others. The good news is that, the more you do it, the more you learn and the better you get at fixing problems. Since many products have similar troubleshooting steps, you may find that after awhile, you don't even need the manual to find solutions to the problems you encounter.
"Sync" is short for synchronize. When you sync a device, such as a cell phone, PDA, or iPod, you synchronize it with data on your computer. This is typically done by connecting the device to your computer via a USB or wireless Bluetooth connection. For example, you might sync the address book stored on your computer with your cell phone to update the contacts. If you have an iPod, you may connect it to your computer to sync songs, videos, and other data using Apple iTunes.
When you sync a device with your computer, it typically updates both device and the computer with the most recent information. This is also referred to as "merging" the data. For example, if you have added a phone number to your phone since the last time you synced it with your computer, that number will be added to your computer's address book. Similarly, any numbers entered into the computer's address book since the last sync will be added to the phone. Most syncing programs also remove entries that have been deleted on either the device or the computer since the last sync.
Since many devices can be synced with a single computer, the computer is often referred to as the "hub" for syncing portable electronics. For example, you might be able to sync an iPod, Blackberry, and PDA using the same address book on your computer. However, you may need to use a different syncing program for each device, since most use a proprietary software utility to sync with the computer. Common syncing programs include iTunes, The Missing Sync, Palm Desktop, and iSync.
A dot matrix is a 2D matrix of dots that can represent images, symbols, or characters. They are used for electronic displays, such as computer monitors and LED screens, as well as printed output.
In a dot matrix display, the images are estimated using a discrete set of dots instead of lines and shapes. Therefore, the more dots that are used, the more clear and accurate the image representation will be. For example, a 16x16 dot matrix can represent the letter "S" more accurately than a 8x8 matrix. If enough dots are used, the image will appear as a contiguous display rather than a group of dots. This is because the human eye blends the dots together to create a coherent image. For example, newspaper print is made up of dot matrixes, but it is hard to notice unless you look very closely at the paper.
Bitmap images on a computer screen are also dot matrixes, since they are made up of a rectangular grid of pixels. If you look closely enough at your monitor, you may even be able to see the dots that make up the image. But be nice to your eyes and don't stare too long!
While "dot matrix" has a broad definition, it can also be used to describe a specific type of printer. Dot matrix printers, or "impact printers," were introduced in the 1970s. These printers typically use the kind of paper with small holes on each side that are used to feed the paper through the printer. They are called dot matrix printers because they use a matrix of dots to print each character. While they do not have a very high resolution, dot matrix printers are an effective way of printing basic text documents. Therefore, while most businesses now use inkjet or laser printers, some organizations still find inkjet printers to be an efficient printing solution.
Tuesday, July 27, 2010
x AND y retuns True if both x and y are true, otherwise the expression returns False.
NOT x returns True if x is false (or null) and False if x is true.
x OR y returns True if either x or y or both are true; only if they are both false will it return False.
x XOR y returns True if either x or y are true, but not both. If x and y are both true or false, the statement will return False.
While boolean expressions are what drive the CPUs in computers, they can also be used by computer users. For example, when searching for information on the Web, many search engines accept boolean operators in the search phrases (i.e. "Yamaha AND piano NOT motorcycle"). Programmers often use boolean expressions in software development to control loops and variables as well.