Epson MX-80 User Manual page 26

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Chapter 9

The programming in line 30 is a bit more exotic. We can quickly see that it

consists of only one LPRINT statement to " p u s h " one TAB, and four control

characters to the Printer. The control codes are of course in Appendix B, but

are also listed here "in order of appearance".

15 stands for COMPRESSED CHARACTER mode

14 stands for DOUBLE WIDTH mode

27 stands for "ESCAPE"

71 is ASCII for the letter " G " , code for DOUBLE STRIKE

which forces us to gosub to another

topic.

The Great Escape

The MX-80 recognizes 13 so called "Escape Codes". They are similar to (and

really part of) the control codes under discussion. The Escape codes should not

be confused with the escape key which some computers have, tho they are shirt-

tail relatives.

We send the special code CHR$(27), which means "ESCAPE", down the line

immediately before another code which requires that ESCAPE. These special

code clusters are logically called "escape codes". We can either build them into a

program or send them from the command level, just as we did before with the

simple control codes. We will learn how to use each "escape code" as it is needed.

Our First Escape Code

Escape " G " stands for DOUBLE STRIKE. (Not double width.) Everything on a

program line which contains an Escape G is printed TWICE by the print head.

Before the second time it is printed, however, the paper is rolled up just 1/2 16th

of an inch to help fill in the spaces between the dots printed on the first pass. The

result looks very bold and solid, almost like it came from a regular typewriter.

Pretty Clever.

Further, once the " G " switch is thrown, everything which follows is DOUBLE

PRINTED until an ESCAPE " H " message is sent, returning printing to normal.

(The ASCII code number for " H " is 72.)

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