DEC LA120 EMULATION
Introduction
This section describes the control codes and escape sequences comprising DEC LA120 emulation. This emulation may be selected by setting “Emulation” to “LA120” in the interface setup menu, or via software with the ESC ESC 5 sequence. While this emulation is selected, control codes and escape sequences from other emulations are not available.
Control codes and escape sequences are used to control printer operation. An ASCII control code is a single character in the range 00 hex through 1F hex, and 7F hex. The ESC (Escape) control code (1B hex) is used to introduce character strings called escape sequences, which provide an extension of the commands available with ASCII control codes.
The LA120 control codes and escape sequences follow the standards of the ANSI X3.64 specification. Many ANSI escape sequences begin with a two character Control Sequence Introducer (CSI), Escape Left Square Bracket (ESC [, 1B 5B hex). If
Some escape sequences accept one or more numeric parameters. A numeric parameter is a decimal number represented by a string of ASCII decimal digits (“0” through “9”). Leading zeros may be supplied, but are not necessary. Due to implementation constraints, the largest value that can be accepted is decimal 255. Larger values will be treated as zero. Omitting a numeric parameter is equivalent to supplying a value of zero.
If a sequence accepts one numeric parameter, it will be represented as “n”. If a sequence accepts more than one numeric parameter, they will be represented as “n1; n2; ... nx”. Note that multiple numeric parameters are separated by a semicolon.
Most LA120 escape sequences will assume one of the following formats:
ESC f | (no numeric parameters) |
ESC n f | (one numeric parameter) |
ESC n1; n2; ... nx f | (two or more numeric parameters) |
The “f” at the end of the escape sequence represents the final character. It terminates the sequence, and specifies the function to be performed.
Spaces are used when documenting escape sequences to increase readability. The spaces within the sequences are for readability only; they are not part of the sequences themselves. Characters that appear in italics (such as “n” and “f” above) are not sent to the printer as is; they are used as a place holder indicating that some value must be supplied.
Multiple character strings without intervening spaces typically represent control codes. For example, BS is the Backspace control code (08 hex), not the two characters “B” and “S” (42 and 53 hex). An ASCII Control Code Table is provided on page 139 for your convenience. If you have any doubt about how to interpret a documented control code or escape sequence, refer to the hex representation in the provided example. This should clarify any ambiguity. The examples may also be helpful when analyzing a hex dump (see Hex Dump chapter) printed by the printer.
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