Epson LX-90 User Manual download pdf (Page 78)

Some software changes one or more codes when sending them to

the printer. The ability of the LX-90 to dump in hexadecimal lets you

determine which codes are creating problems for your system.

A data dump printout of a program shows you exactly what the

printer is receiving, regardless of what the computer is sending. The

following test program lets you check to see what codes, if any, are

problems for your software. This program is in BASIC; use an equiv-

alent program for another programming language.

10 FOR X=0 TO 255

20 LPRINT CHR$(X);

NEXT X

Put the printer in data dump mode and then RUN the program.

Remember to press the ON LINE button to make the LX-90 print the

final line. Then compare your printout with the list of hex codes in

order in Appendix A. If any are skipped or repeated, you will know

that your software changes some codes before it sends them to the

printer.

For example, in the lines below, which are the first two lines of the

printout of the test program run with IBM PC BASIC, you can see

that in this case BASIC adds hex 0A, which is the code for line feed,

after hex 0D, the code for a carriage return. You will also notice that

the program does not send hex

1A,

which is decimal 26. Both of these

characteristics are discussed in the next section.

The data dumping capability can help you debug a program

quickly. Appendix A will help you translate the hex codes to ASCII

equivalents.

IBM PC BASIC Solutions

There are three problems in using the IBM Personal Computer

BASIC to drive a printer. First, the IBM PC BASIC inserts a carriage-

return/line-feed (CR-LF) after each 80 characters you send it. Second,

it adds an LF to each CR in an LPRINT statement. Third, it will not

send hex

(decimal 26).

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Epson LX-90 User Manual Page 78