Epson FX-80 User Manual page 314

These codes can be sent directly to the printer by POKEing them to
a special memory location where they are immediately forwarded to
the printer. The format is:
POKE 14312,N
where N is the decimal value of the code you wish to send to the
printer. This works fine as long as the printer is ready to receive the
data when you are ready to send it. On the TRS-80, the printer's
readiness is assured if location 14312 contains a decimal 63.
It is best to first test to see if the printer is ready with:
1~~
IF PEEK(14312)<>63 THEN
1~~
This puts the program into a continuous loop until the printer is
ready to receive data. If data is sent while the printer is "out to lunch,"
it will be lost.
To show how similar these commands can be from system to sys-
tem, here is the same concept implemented on the Apple II Plus:
1~~
IF
PEEK(496~1»127
THEN
1~~
2~~ POKE 49296,N
The printer's status is stored in location 49601 and the outgoing values
are sent to 49296.
Using a Special Printer Driver
An
even better (but more difficult) way to overcome these problems
is to modify the printer driver so that the codes are passed correctly to
the printer without any PEEKs or POKEs. Unfortunately, modifying a
printer driver requires a knowledge of machine-language program-
ming and a familiarity with your computer's operating system. If you
are not well versed in these areas, join the dub. Perhaps your com-
puter dealer knows of a solution. Those who have mastered the ma-
chines, let it be known in the trade journals.
The following PRINTER DRIVER is written for the Model I TRS-80
by Bob Boothe and reprinted with the kind permission of 80 Micro-
computing. The program pokes a machine-language printer driver
program (stored in line 10) into memory, then tells the system where
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