alphanumeric characters and special symbols. For instance, 65 represents the capital letter “A”, while 90 represents the capital letter “Z.” On the P-80, the graphics character set is stored at codes 128 through 159. Other ASCII numbers control computer and printer functions.

Table 4-1 summarizes the range of the ASCII codes used by the P-80. Appendix B summarizes the functions for each of the ASCII control codes.

Note: Codes can be expressed in binary, hexadecimal, or decimal form. For ease of understanding, we use the decimal form.

Table 4-1.The P-80 and ASCII Codes

ASCII code group

 

P-80Interpretation

1 to 32

Printer control

codes

33 to 126

Standard

(roman) character set

128 to 159

Graphics

character set

In summary, some ASCII codes produce standard characters and special symbols, some produce graphics characters, and others control the printer’s functions.

Using Control Codes

Most of the time you don’t have to give this code system much thought. When you are using a word processing system, you press the letter A on the keyboard, and the computer prints the letter A on the printer.

Some ASCII codes, however, don’t have characters on the key- board. The most important of these are the ASCII codes that have values less than 32. As mentioned above, these codes are the printer control codes. Most keyboards can produce these codes by holding down the control key (often marked CTRL) while pressing a letter key. The combination of CTRL/M produces ASCII 13, which is the code to start a new line, and referred to as a carriage return. The

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