MacDirectory Magazine

Summer-Fall 2008 (#38)

MacDirectory magazine is the premiere creative lifestyle magazine for Apple enthusiasts featuring interviews, in-depth tech reviews, Apple news, insights, latest Apple patents, apps, market analysis, entertainment and more.

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30 MacDirectory DEPARTMENT AN APPLE A DAY > TECH TERMS MADE SIMPLE WORDS BY MARY ROSENTHOL ARP > Stands for "Address Resolution Protocol." ARP is a protocol used for mapping an IP address to a computer connected to a local network LAN. Since each computer has a unique physical address called a MAC address, the ARP converts the IP address to the MAC address. This ensures each computer has its own network identification. The Address Resolution Protocol is used when information sent to a network arrives at the gateway, which serves as the entrance point to the network. The gateway uses the ARP to locate the MAC address of the computer, based on the IP address the data is being sent to. The ARP typically looks up this information in a table called the "ARP cache." If the address is found, the information is relayed to the gateway, which will send the incoming data to the appropriate machine. It may also convert the data to the correct network format if necessary. Connectile Dysfunction > Slang term used to describe one's inability to obtain or maintain an Internet connection. A user who is experiencing connection drops would say their ISP is suffering from connectile dysfunction. Disk Image > A software copy of a physical disk. It saves the entire data from the disk, including the file structure and all files and folders from the disk, in a single file. Because disk images are exact copies, or "clones," of original disks, they can be used to duplicate disks or serve as full backups in case of a system restore. Disk images can be created from both hard disks and optical media, such as CDs and DVDs. However, optical media images are technically called "disc images" instead of "disk images." Several programs, such as Nero, IsoBuster, and Norton Ghost can be used to make disk images for Windows. Programs such as Apple Disk Utility and Roxio Toast can create disk images for Mac OS X. Gopher > The technology was invented at the University of Minnesota, whose mascot is, not surprisingly, the Golden Gopher. The gopher system allows people to search for and retrieve information using a text interface. The technology is based on a client-server structure, where a gopher client program is used to search gopher servers. These servers can store documents, articles, programs, and other information. Instead of hyperlinks, the gopher interface uses menus of links to other documents and programs. The University of Minnesota began a licensing program for the gopher technology in 1993 as the use of gopher was spreading rapidly over the Internet. However, this was around the same time that the World Wide Web was introduced. Because the Web used hypertext and images, it soon became the preferred way to search and browse for information. While there are still servers and client programs that use gopher technology, their use is not nearly as widespread as the Web. Iteration > The repetition of a function or process in a computer program. Iterations of functions are common in computer programming, since they allow multiple blocks of data to be processed in sequence. This is typically done using a "while loop" or "for loop" (see the examples below). These loops will repeat a process until a certain number or case is reached. Recursive functions also use iteration, though instead of repeating a process, the entire function repeats itself. A practical example of how iterations are used is a PHP Web page that lists data from a table in a database. In order to display the table on the Web, the function might write each row in HTML using data from the database until the last row of data is reached. In this case, each row of the table would be created by an iteration of the PHP function. Spaghetti marketing > Slang term used to describe the random spending of marketing dollars in an unorganized, unplanned way. The slang term is derived from cooking spaghetti where one might, "throw spaghetti against the wall to see if it sticks". Unmounting > This makes a disk inaccessible by the computer. In order for a disk to be unmounted, it must first be mounted. Since unmounting a disk prevents the computer from accessing it, there is no risk of the disk being disconnected in the middle of a data transfer. Before removing an external data storage device, the disk should first be unmounted to avoid data corruption.

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