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 dont 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 dot matrix printers to be an efficient printing solution.
Posts made by Renato
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Dot Matrix
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Direct3D
Direct3D is an application program interface (API) developed by Microsoft that provides a set of commands and functions for manipulating 3D objects. By using Direct3D commands, software developers can take advantage of many prewritten functions. This allows programmers to write significantly less code than if they had to write all the functions from scratch. Direct3D makes it relatively easy to manage three-dimensional objects, including lighting and shadows as well.
In order for a software program to use Direct3D commands, the computers video card or graphics accelerator device must support Direct3D. Fortunately, just about all video cards made for PCs offer Direct3D support. While many video games and other programs use Direct3D, OpenGL is a more widely used standard. -
Diode
A diode is an electrical component designed to conduct electric current in only one direction. It has two ends (or terminals), each with an electrode of a different charge. The anode end has a positive charge relative to the negatively charged cathode end. Current naturally flows in the direction from the anode to the cathode.
Diodes commonly serve as switches, allowing or preventing the flow of current. For example, current can be stopped by simply reversing an active diode inside an electrical circuit. Flipping the diode back to the original position will allow electricity to continue flowing through the circuit. Multiple diodes within a circuit can be used as logic gates, performing AND and OR functions.
While current generally flows through a diode in one direction, in some cases the current can be reversed. If the negative voltage applied to a diode exceeds the breakdown voltage, the current will begin flowing in the opposite direction. The breakdown voltage of a typical diode ranges from -50 to -100 volts, though the amount can be significantly less or more based on the design and materials used in the diode. Some diodes can be damaged by the reverse flow of current, while others are designed to allow current to flow in both directions. Zener diodes, for instance, are designed with specific breakdown voltages for different applications.
Another common type of diode is a light-emitting diode, or LED. Light emitting diodes generate visible light when current passes between the anode and cathode though a space called the p-n junction. The electrical charge in this space produces light in different colors depending on the charge and materials used in the diode.
Diode Diagram Showing Current Flow
Actual Diode on Electrical Wire -
Dialog Box
As the name implies, a dialog box serves to initiate a dialog with the user. It is a window that pops up on the screen with options that the user can select. After the selections have been made, the user can typically click OK to enter the changes or Cancel to discard the selections. It is customary for menu options that include an ellipsis at the end, such as Preferences... or Save As..., to open a dialog box when selected.
For example, if a user selects Internet Options... from the Options menu in Internet Explorer, a dialog box will pop up allowing the user to choose the default home page, change the security settings, empty the browser cache, and modify several other settings. Once the selections have been made, the user can click OK to use the new settings, or Cancel to discard the changes. Some Windows programs also have an Apply option that activates the selections without closing the dialog box.
When a user selects Open... from the File menu, an Open dialog box appears, allowing the user to browse the hard drive and other disks for files to open. When Save As... is chosen from the File menu, a Close dialog box pops up, allowing the user to type the name of the file and choose where to save it. While dialog boxes may not seem too exciting, they provide an intuitive way to communicate with the computer and are an essential part of todays computer interfaces. -
Default Program
A default program is an application that opens a file when you double-click it. For example, if you double-click a .TXT file in Windows and it automatically opens in Notepad, then Notepad is the default program for files with a .txt extension. If the file opens in Microsoft Word, then Microsoft Word is the default program.
Default programs are necessary since many file types can be opened by more than one program. For example, your computer may have over a dozen applications that can open .JPG files. Therefore, the operating system needs to know which program to open by default when you double-click a JPEG image file.
Both Windows and Macintosh computers store a list of default programs for each file extension. These relationships between programs and file extensions are also called file associations. Both the Windows and Macintosh operating systems allow you to change file associations if you dont like the default program that is associated with a certain file type. For example, if you prefer to play MP3 files in iTunes rather than Windows Media Player, you can change the .mp3 file association to iTunes. This will set iTunes as the default program for all .MP3 files.
Windows 7 has a built-in utility for configuring file associations called Default Programs. This tool allows you to assign specific programs to one or more file extensions using a simple graphical interface. It also displays what file extensions are associated with each installed application. For more information on using the Windows 7 Default Programs tool, view the FileInfo.com Default Programs Help Article.
While Mac OS X does not include a Default Programs tool, you can simply right-click a file and choose Open With… to select a different program to open it. If you want to change the default program for a specific file, select the file and choose File → Get Info. Then select a different program in the Open with: section of the window. If you want to change the default program for all files with the same extension, press the Change All… button. -
Coaxial Cable
Coaxial (or “coax”) cable is a common type of cable used for transmitting data over long distances. It can carry either an analog or digital signal. While coax cables have many applications, they are most commonly used to transmit cable TV and Internet signals.
Coax cables that run underground are typically thicker and more heavily insulated than the cables that connect your cable box or cable modem to the wall outlet. However, they all transmit data via a thin copper line in the middle of the cable. This wire is surrounded by a layer of insulation comprised of non-conductive or “dielectric” material. The dielectric layer is covered with one or more metallic shields that provides additional protection from signal interference. Finally, a protective plastic outer layer surrounds the entire cable.
The heavy duty design of coaxial cables is what allows them to carry data over long distances with minimum signal degradation. In many cases, coax cables laid by cable companies several decades ago are sufficient to provide HDTV and high-speed Internet access simultaneously. However, certain coax cables (such as RG-59 cables) are designed for low bandwidth applications, like connecting a VCR to a TV, and may not provide enough bandwidth to carry a full HDTV signal. Coax cables labeled as “RG-6” are a better choice for HDTV and cable Internet service. -
Boot Disk
A boot disk is actually not a computer disk in the shape of a boot. If it was, most disk drives would have a difficult time reading it. Instead, a boot disk is a disk that a computer can start up or boot from. The most common type of boot disk is an internal hard drive, which most computers use to start up from. The operating system installed on the hard drive is loaded during the boot process.
However, most computers allow you to boot from other disks, including external Firewire hard drives, CD-ROMs, DVD-ROMs, and floppy disks. In order to function as boot disks, these disks need to have an operating system installed that is understandable by the computer. This can either be a full-blown operating system like Windows or Mac OS X, or a small utility operating system, such as Norton Utilities or DiskWarrior.
CD and DVD boot disks are often used to start up a computer when the operating system on the internal hard drive wont load. This can happen when bad data blocks or other errors occur on the disk. By running a disk repair utility from the CD or DVD, you can often fix the hard drive and restart from it, using the full operating system. -
Blog
Short for Web Log, this term refers to a list of journal entries posted on a Web page. Anybody who knows how to create and publish a Web page can publish their own blog. Some Web hosts have made it even easier by creating an interface where users can simply type a text entry and hit publish to publish their blog.
Because of the simplicity of creating a blog, many people (often young kids and adults) have found a new presence on the Web. Instead of writing confidential entries in a book that no one is supposed to see, people now can share their personal feelings and experiences with thousands of people around the world. Blogs are typically updated daily, monthly, or anywhere in between. Blog may also be used as a verb, as in Wow, Matt sure blogged a lot last week. -
RE: Barebones
A barebones PC is a computer that has minimal components. A typical barebones system includes a case, motherboard, CPU, hard drive, RAM, and power supply. Most barebones systems are sold as kits, in which the components must be assembled by the user.
Since barebones PCs usually do not come preassembled, they are not designed for the average computer user. Instead, barebones kits are aimed at computer enthusiasts and users who prefer to build their own PCs. By purchasing only specific components, a user can fully customize his computer system and avoid paying for unwanted extras. For example, if you buy a barebones kit, you can choose your own keyboard and mouse, since they are not included. Also, no software is bundled with barebones systems, so you avoid paying for software you dont need. Additionally, most barebones systems do not come with an operating system, so you can choose to install any operating system that is compatible with the hardware.
Nearly all barebones PCs are desktop computers since they are the most customizable. However, some companies also offer barebone laptop systems, or barebooks, which can be homebuilt. While Macintosh computers now use most of the same components as PCs, the Mac OS X operating system requires proprietary hardware to run. Therefore, barebones systems are generally built to run either Windows or Linux. -
Applet
An applet is a small application designed to run within another application. While the term applet is sometimes used to describe small programs included with a computers operating system, it usually refers to Java applets, or small applications written in the Java programming language.
Unlike ordinary applications, Java applets cannot be run directly by the operating system. Instead, they must run within the Java Runtime Environment (JRE), or within another program that includes a Java plug-in. If there is no JRE installed, Java applets will not run. Fortunately, Java is freely available for Windows, Mac, and Linux systems, which means you can easily download and install the appropriate JRE for your system. Since Java applets run within the JRE and are not executed by the operating system, they are crossplatform, meaning a single applet can run on Windows, Mac, and Linux systems.
While applets can serve as basic desktop applications, they have limited access to system resources and therefore are not ideal for complex programs. However, their small size and crossplatform nature make them suitable for Web-based applications. Examples of applets designed to run in web browsers include calculators, drawing programs, animations, and video games. Web-based applets can run in any browser on any operating system and long as the Java plug-in is installed.
During the early years of the Web, Java applets provided a way for webmasters to add interactive features that were not possible with basic HTML. However, in recent years, applets have been slowly replaced by newer technologies such as jQuery and HTML 5. Some browsers, like Google Chrome, no longer support the <applet> tag, and others, like Apple Safari, do not even enable Java by default. Since web developers cannot fully rely on Java support from web browsers, applets are no longer a common way to provide interactive content on the Web. -
Antivirus
Antivirus software is a type of utility used for scanning and removing viruses from your computer. While many types of antivirus (or anti-virus) programs exist, their primary purpose is to protect computers from viruses and remove any viruses that are found.
Most antivirus programs include both automatic and manual scanning capabilities. The automatic scan may check files that are downloaded from the Internet, discs that are inserted into the computer, and files that are created by software installers. The automatic scan may also scan the entire hard drive on a regular basis. The manual scan option allows you to scan individual files or your entire system whenever you feel it is necessary.
Since new viruses are constantly being created by computer hackers, antivirus programs must keep an updated database of virus types. This database includes a list of virus definitions that the antivirus software references when scanning files. Since new viruses are frequently distributed, it is important to keep your softwares virus database up-to-date. Fortunately, most antivirus programs automatically update the virus database on a regular basis.
While antivirus software is primarily designed to protect computers against viruses, many antivirus programs now protect against other types of malware, such as spyware, adware, and rootkits as well. Antivirus software may also be bundled with firewall features, which helps prevent unauthorized access to your computer. Utilities that include both antivirus and firewall capabilities are typically branded Internet Security software or something similar.
While antivirus programs are available for Windows, Macintosh, and Unix platforms, most antivirus software is sold for Windows systems. This is because most viruses are targeted towards Windows computers and therefore virus protection is especially important for Windows users. If you are a Windows user, it is smart to have at least one antivirus program installed on your computer. Examples of common antivirus programs include Norton Antivirus, Kaspersky Anti-Virus, and ZoneAlarm Antivirus. -
802.11n
802.11n is a wireless (Wi-Fi) standard that was introduced in 2007. It supports a longer range and higher wireless transfer rates than the previous standard, 802.11g.
802.11n devices support MIMO (multiple in, multiple out) data transfers, which can transmit multiple streams of data at once. This technology effectively doubles the range of a wireless device. Therefore, a wireless router that uses 802.11n may have twice the radius of coverage as an 802.11g router. This means a single 802.11n router may cover an entire household, whereas an 802.11g router might require additional routers to bridge the signal.
The previous 802.11g standard supported transfer rates of up to 54 Mbps. Devices that use 802.11n can transfer data over 100 Mbps. With an optimized configuration, the 802.11n standard can theoretically support transfer rates of up to 500 Mbps. That is five times faster than a standard 100Base-T wired Ethernet network.
So if your residence is not wired with an Ethernet network, its not a big deal. Wireless technology can finally keep pace with the wired network. Of course, with the faster speeds and larger range that 802.11n provides, it is more important than ever to password protect your wireless network. -
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