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[ The PC Guide | Systems and Components Reference Guide | Keyboards | Keyboard Software Issues ]

<Alt> Key ASCII Code Generation

The last subject I want to cover in my discussion of keyboard software matters is ASCII code generation. This is a neat feature that many people don't even know about, which lets you access some of the more obscure characters in the standard ASCII character set directly, even ones that have no regular keyboard keys.

To use this feature, you may need to enable the numeric keypad on your keyboard by pressing the <Num Lock> key. Open a DOS prompt box. Then hold down the <Alt> key, and while it is held down, enter a number on the numeric keypad from 32 to 255 (you can do 1 to 31 as well, but these generate control characters). After entering the code, let go of the <Alt> key and the appropriate character will appear.

You can use this to generate mundane symbols, the same as if you typed them; for example, <Alt>+65 is the letter "A", and <Alt>+123 the "{" character. But these codes are more useful for unusual characters that don't have a key on the keyboard. For example, try <Alt>+130; this generates the "e" with an acute accent (""), useful for the occasional French word. <Alt>+248 generates a degree symbol ("") for temperatures. There are many more of course. Within DOS there are a number of special characters created for special tasks, "ASCII graphics" and so forth, which can be useful at times.

To know which characters go with which codes, you need to consult an ASCII table--or you can just go by trial and error. The characters generated also depend on the application into which you enter them, since it decides what to do with each character.   You can find a partial ASCII table here (though it only shows the first 127 characters, not all 255, because HTML doesn't support the DOS graphics characters).

Note: This function actually creates characters, not scan codes, so you use the ASCII value of the character you want, not its scan code (many of these characters have no scan codes, which is sort of the whole point...)

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