ASA carriage control characters

ASA control characters are simple printing command characters used by mainframe printers to control the movement of paper through line printers. These commands are presented as special characters in the first column of each text line to be printed, and affect how the paper is advanced before the line is printed.

"ASA" is the abbreviation of the American Standards Association, a former name for the American National Standards Institute (ANSI), which is believed to have sanctioned these control characters.

Operation

ASA Character	Action	ASCII Equivalent
blank	Advance 1 line (single spacing)	CR LF
1	Advance to next page (form feed)	CR FF
2–9, A, B, C	Advance to vertical tab stop	CR VT (approximately)
0	Advance 2 lines (double spacing)	CR LF LF
-	Advance 3 lines (triple spacing)	CR LF LF LF
+	Do not advance any lines before printing, overstrike previous line with current line	CR

Overstriking can be used to make boldface text by printing the same line twice without advancing the paper. It can also be used to make underlined text by printing a line of underscore characters atop the text.

Mainframe printers have 12 channels (1 through 9 and A through C) that can be assigned a fixed position on the page, allowing the printer to skip a variable distance down the page to a fixed location. Normally only channel 1 is preassigned, to the top of the page.

ASA carriage control characters are still used for printer output from mainframe applications and software today, and are not limited to seasoned software or applications dating from the days of the line printer. ASA carriage control characters are interpreted by other software before being printed on modern computer printers.

Example output containing ASA carriage control characters:

1This is the first line on the page
0This is the third line on the page
-This is the 6th line on the page
 This is the 7th line on the page
+____    the                      - Overstrike the 7th line 

Example as printed output:

This is the first line on the page

This is the third line on the page


This is the 6th line on the page
This is the 7th line on the page - Overstrike the 7th line

See also

• Carriage control tape
• IBM Machine Code Printer Control Characters

External links

• More elaborate description at Felgall Mainframe
• IBM Printing Reference for AIX compilers
• First-character forms-control data definition [1]