CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [247]
Figure 15-11 ASCII characters
ASCII was the first universal file format. Virtually every type of program—word processors, spreadsheets, databases, presentation programs—can read and write text files. However, text files have severe limitations. A text file can’t store important information such as shapes, colors, margins, or text attributes (bold, underline, font, and so on). Therefore, even though text files are fairly universal, they are also limited to the 256 ASCII characters.
Even in the most basic text, you need to perform a number of actions beyond just printing simple characters. For example, how does the program reading the text file know when to start a new line? This is where the first 32 ASCII characters come into play. These first 32 characters are special commands (actually, some of them are both commands and characters). For example, the ASCII value 7 can be either a large dot or a command to play a note (bell) on the PC speaker. ASCII value 9 is a Tab. ASCII value 27 is an Escape.
ASCII worked well for years, but as computers became used worldwide, the industry began to run into a problem: There are a lot more than 256 characters used all over the world! Nobody could use Arabic, Greek, Hebrew, or even Braille! In 1991, the Unicode Consortium, an international standards group, introduced Unicode. Basic Unicode is a 16-bit code that covers every character for the most common languages, plus a few thousand symbols. With Unicode you can make just about any character or symbol you might imagine—plus a few thousand more you’d never even think of. The first 256 Unicode characters are exactly the same as ASCII characters, making for easy backward compatibility.
A lot of e-mail programs can use Unicode characters, as can Internet message boards such as my Tech Forums. You can use Unicode characters to accent your writing or simply to spell a person’s name correctly—Martin Acuña—when you address him. Here’s how you do it.
1. Open a text editing program such as Notepad in the Windows GUI.
2. Hold down the ALT key on your keyboard and, referring to Figure 15-11, press numbers on your keyboard’s number pad to enter special characters. For example, pressing ALT-164 should display an ñ, whereas ALT-168 shows a ¿.
3. If you have access to the Internet, surf over to the Tech Forums (www.totalsem.com/techforum/index.php) and say howdy. Include some Unicode in your post, of course!
Drives and Folders
When working from the command line, you need to be able to focus the prompt at the specific drive and folder that contains the files or programs with which you want to work. This can be a little more complicated than it seems, especially in Windows 2000, Windows XP, and Windows Vista.
At boot, Windows assigns a drive letter (or name) to each hard drive partition and to each floppy or other disk drive. The first floppy drive is called A:, and the second, if installed, is called B:. Hard drives usually start with the letter C: and can continue to Z: if necessary. Optical drives by default get the next available drive letter after the last hard drive. Windows 2000, XP, and Vista enable you to change the default lettering for drives, so you’re likely to see all sorts of lettering schemes. On top of that, Windows 2000, XP, and Vista let you mount a hard drive as a volume in another drive.
Whatever the names of the drives, Windows uses a hierarchical directory tree to organize the contents of these drives. All files are put into groups Windows calls folders, although you’ll often hear techs use the term directory rather than folder, a holdover from the true DOS days. Any file not in a folder within the tree—that is, any file in the folder at the root