Month: October 2015

Tech Terms: CMYK

Stands for “Cyan Magenta Yellow Black.” These are the four basic colors used for printing color images. Unlike RGB (red, green, blue), which is used for creating images on your computer screen, CMYK colors are “subtractive.” This means the colors get darker as you blend them together. Since RGB colors are used for light, not pigments, the colors grow brighter as you blend them or increase their intensity.

Technically, adding equal amounts of pure cyan, magenta, and yellow should produce black. However, because of impurities in the inks, true black is difficult to create by blending the colors together. This is why black (K) ink is typically included with the three other colors. The letter “K” is used to avoid confusion with blue in RGB.


Tech Terms: Bus

While the wheels on the bus may go “round and round,” data on a computer’s bus goes up and down. Each bus inside a computer consists of set of wires that allow data to be passed back and forth. Most computers have several buses that transmit data to different parts of the machine. Each bus has a certain size, measured in bits (such as 32-bit or 64-bit), that determines how much data can travel across the bus at one time. Buses also have a certain speed, measured in megahertz, which determines how fast the data can travel.

The computer’s primary bus is called the frontside bus and connects the CPU to the rest of the components on the motherboard. Expansion buses, such as PCI and AGP, allow data to move to and from expansion cards, including video cards and other I/O devices. While there are several buses inside a computer, the speed of the frontside bus is the most important, as it determines how fast data can move in and out of the processor.


Tech Terms: MySQL

MySQL, pronounced either “My S-Q-L” or “My Sequel,” is an open source relational database management system. It is based on the structure query language (SQL), which is used for adding, removing, and modifying information in the database. Standard SQL commands, such as ADD, DROP, INSERT, and UPDATE can be used with MySQL.

MySQL can be used for a variety of applications, but is most commonly found on Web servers. A website that uses MySQL may include Web pages that access information from a database. These pages are often referred to as “dynamic,” meaning the content of each page is generated from a database as the page loads. Websites that use dynamic Web pages are often referred to as database-driven websites.

Many database-driven websites that use MySQL also use a Web scripting language like PHP to access information from the database. MySQL commands can be incorporated into the PHP code, allowing part or all of a Web page to be generated from database information. Because both MySQL and PHP are both open source (meaning they are free to download and use), the PHP/MySQL combination has become a popular choice for database-driven websites.


Tech Terms: Windows XP

Microsoft Windows XP was introduced in 2001 and is the most significant upgrade to the Windows operating system since Windows 95. The previous version of Windows, called Windows Me (or Millennium Edition) still had the look and feel of Windows 95 and was known to have stability issues and incompatibilities with certain hardware.

Windows XP addressed many issues of its predecessor and added a number of other improvements as well. It is a stable operating system since it is built on the Windows 2000 kernel, which is known for its reliability. XP also has a new, more modern look, and an interface that is more easy to navigate than previous versions of Windows. While not written from the ground up, like Mac OS X, Windows XP is a substantial system update. The letters “XP” stand for “eXPerience,” meaning the operating system is meant to be a new type of user experience.


Tech Terms: OS X

OS X is Apple’s operating system that runs on Macintosh computers. It was first released in 2001 and over the next few years replaced Mac OS 9 (also known as Mac OS Classic) as the standard OS for Macs. It was called “Mac OS X” until version OS X 10.8, when Apple dropped “Mac” from the name.

OS X was originally built from NeXTSTEP, an operating system designed by NeXT, which Apple acquired when Steve Jobs returned to Apple in 1997. Like NeXTSTEP, OS X is based on Unix and uses the same Mach kernel. This kernel provides OS X with better multithreading capabilities and improved memory management compared to Mac OS Classic. While the change forced Mac developers to rewrite their software programs, it provided necessary performance improvements and scalability for future generations of Macs.

The OS X desktop interface is called the Finder and includes several standard features. OS X does not have a task bar like Windows, but instead includes a menu bar, which is fixed at the top of the screen. The menu bar options change depending on what application is currently running and is only hidden when full screen mode is enabled. The Finder also includes a Dock, which is displayed by default on the bottom of the screen. The Dock provides easy one-click access to frequently used applications and files. The Finder also displays a user-selectable desktop background that serves as a backdrop for icons and open windows.

When you start up a Mac, OS X loads automatically. It serves as the fundamental user interface, but also works behind the scenes, managing processes and applications. For example, when you double-click an application icon, OS X launches the corresponding program and provides memory to the application while it is running. It reallocates memory as necessary and frees up used memory when an application is quit. OS X also includes an extensive API, or library of functions, that developers can use when writing Mac programs.

While the OS X interface remains similar to the original version released in 2001, it has gone through several updates, which have each added numerous new features to the operating system. Below is a list of the different versions of OS X, along with their code names.

Mac OS X 10.0 (Cheetah)
Mac OS X 10.1 (Puma)
Mac OS X 10.2 (Jaguar)
Mac OS X 10.3 (Panther)
Mac OS X 10.4 (Tiger)
Mac OS X 10.5 (Leopard)
Mac OS X 10.6 (Snow Leopard)
Mac OS X 10.7 (Lion)
OS X 10.8 (Mountain Lion)
OS X 10.9 (Mavericks)
OS X 10.10 (Yosemite)


Tech Terms: Dashboard

Dashboard is a user-interface feature Apple introduced with the release of Mac OS X 10.4 Tiger. It allows access to all kinds of “widgets” that show the time, weather, stock prices, phone numbers, and other useful data. With the Tiger operating system, Apple included widgets that do all these things, plus a calculator, language translator, dictionary, address book, calendar, unit converter, and iTunes controller. Besides the bundled widgets, there are also hundreds of other widgets available from third parties that allow users to play games, check traffic conditions, and view sports scores, just to name a few.

The dashboard of widgets is accessed by clicking the Dashboard application icon, or by simply pressing a keyboard shortcut (F12 by default). Clicking a plus “+” icon in the lower-left hand corner of the screen provides the user with a list of all installed widgets. Clicking the widgets or dragging them onto the desktop makes them active. They can be individually closed by clicking the close box, just like other open windows. Pressing the keyboard shortcut (F12) makes them instantly disappear, removing them from view until the user needs them again.


Tech Terms: OLE

Stands for “Object Linking and Embedding.” It can be pronounced as “O-L-E,” or “Oh-lay!” if you are feeling Spanish. OLE is a framework developed by Microsoft (way back in Windows 3.1) that allows you to take objects from a document in one application and place them in another. For example, OLE may allow you to move an image from a photo-editing program into a word processing document.

The OLE technology was initially created to allow the linking of objects between “compound documents,” or documents that support multiple types of data. Microsoft has since developed OLE into a wider standard, known as the Component Object Model (COM). COM is supported by Mac, Unix, and Windows systems, but is primarily used with Microsoft Windows. The COM framework is the foundation of ActiveX, which allows developers to create interactive content for the Web.


Tech Terms: SOAP

Stands for “Simple Object Access Protocol,” and can do more than just get your hands clean. SOAP is a method of transferring messages, or small amounts of information, over the Internet. SOAP messages are formatted in XML and are typically sent using HTTP (hypertext transfer protocol). Both are widely supported data transmission standards. HTTP, which is the protocol that Web pages are sent over, has the additional advantage of avoiding most network firewalls. Since firewalls usually do not block port 80 (HTTP) traffic, most SOAP messages can pass through without any problems.

Each SOAP message is contained in an “envelope” that includes a header and a body. The header may include the message ID and date the message was sent, while the body contains the actual message. Because SOAP messages all use the same format, they are compatible with many different operating systems and protocols. For example, a user can send a SOAP message from a Windows XP machine to a Unix-based Web server without worrying about the message being altered. The Unix machine can then redirect the message to the appropriate location or open the file using a program on the system. While most SOAP messages are sent over the Web via HTTP, they can also be sent via e-mail, using SMTP.


Tech Terms: Payload

When data is sent over the Internet, each unit transmitted includes both header information and the actual data being sent. The header identifies the source and destination of the packet, while the actual data is referred to as the payload. Because header information, or overhead data, is only used in the transmission process, it is stripped from the packet when it reaches its destination. Therefore, the payload is the only data received by the destination system.


Tech Terms: DTD

Stands for “Document Type Definition.” A DTD defines the tags and attributes used in an XML or HTML document. Any elements defined in a DTD can be used in these documents, along with the predefined tags and attributes that are part of each markup language. The following is an example of a DTD used for defining an automobile:

<!–ENTITY header “Car Details”–>

<!–ELEMENT make (#PCDATA)–>

<!–ELEMENT model (#PCDATA)–>

<!–ATTLIST model doors (two | four) #required–>

<!–ELEMENT year (#PCDATA)–>

<!–ELEMENT engine (#PCDATA)–>

<!–ATTLIST engine transmission (manual | automatic) #required–>

The above DTD first defines the header of the item as “Car Details.” Then it provides elements to define the make and model of the automobile. The “#PCDATA” data type means it can be any text value). The “ATTLIST” tag on the next line provides options for a specific element. In this case, it states that the model can have either two or four doors. The DTD then provides elements for the year and engine type of the car, followed by a choice of either a manual or automatic transmission for the engine.

The above example is a basic DTD that only uses a few data types. Document type definitions used for large XML databases can be thousands of lines long and can include many other data types. Fortunately, DTDs can be easily modified in a text editor whenever changes need to be made.