User's Manual

Control Code Definitions

Chapter

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64 6820 Series 80-Column Printer User’s Manual

Control Code Definitions

Buffers

I/O Buffer

All characters and control codes received by the printer are stored in this

buffer. Characters and controls codes are read from this buffer and acted

upon to f orm the print buffer. Characters are removed from the I/O buffer

as they are processed.

Print (image) Buffer

All characters go through this buffer on their way to the printed page. This

buffer contains the graphic image of the dots to print, from which charac-

ters are rendered. It is cleared when its contents are printed.

Special Notations

The following information d efines notations included in the format defini-

tions of the escape sequences, throughout this section.

Notation Description

(0) Used in the ASCII column of any of the Format definitions, indicates that its value can only be zero

(and not the character “0”). For example: Select Top-Down Printing ESC US (0).

(1) Used in the ASCII column of any of the Format definitions, indicates that its value c an only be one

(and not the character “1”). For example: Select Bottom-Up Printing ESC US (1).

* When a number (at the end of an escape sequence) is marked with an asterisk, then either the value

corresponding to that number or the value of the string character can be used for that number.

For example, if 1* is shown, then either the value (1), or the value of the string character (decimal:

49, hex: 31) can be used.

NUL

he NUL character is represented in the Dec column as 0, in the Hex column as 00, and in the

ASCII column as NUL.

General Printer Control Functions

Backspace

The print buffer is emptied. The print head is moved to the left one char-

acter space (using the current pitch). This can be performed to, but not

beyond, the left margin setting. The backspace is ignored if justification of

right, full, or centered is selected.

Format

Decimal Hex ASCII

8 08 BS

The b ackspace control code (BS) is not reliable when text contains differ-

ent character pitches. For reliable backspacing, use the escape sequence

(ESC “\”), Set Relative Print Position.