Solving The 7-Bit Dilemma - Epson FX-80 User Manual

Now type several characters, and after each press the (ENTER)
key. True to form, the printer just stuffs the characters into its buffer
while it waits for a carriage- return code. To end this version of the
program and print the contents of the buffer, press (ENTER) alone.
Now add this line:
1(21 LPRINT CHR$(27)"i1"
I
Lower-case i
And RUN the program as before. (Use CHR$(lOS)"1 " in place of "il"
if necessary). This time the printer prints each string immediately. It
also feeds the paper so that you can see what is being printed. Play
with this for a while, then, when you are finished playing secretary
with your new typewriter, press (ENTER) alone.
The exit code for Immediate Print Mode is:
LPRINT CHR$(27)"i(2l"
I
Lower-case i
Solving the 7-Bit Dilemma
You'll find lots of references to 7-bit computers in this manual. The
term "7-bit" is not an evaluation of the net worth of such computers,
but rather a description of the number of data lines active in their
printer interfaces. Unfortunately, the inability to turn the eighth data
line on and off is a serious drawback when working with a printer.
There is no way that 7-bit computers can fully exploit all the features
of the printer. But the FX-80 does have a few tricks up its sleeve to give
them a helping hand.
First, there
is
a way to permanently turn the high-order (eighth) bit
on or off, even with 7-bit computers. There are three instructions that
allow a 7-bit computer to control its high-order bit:
(ESC)")" turns the high-order bit ON
(ESC)"
="
turns it OFF
(ESC
~
"#"
returns it to normal
Here's an example of how this works:
76
NEW
1(21 LPRINT CHR$(27)")"
I
Sets eighth bit
2(21 FOR X=65 TO 9(21: LPRINT CHR$(X);: NEXT X
3(21 LPRINT CHR$(27)"="
I
Supresses eighth bit
4(21 FOR X=193 TO 218: LPRINT CHR$(X);: NEXT X
5(21 LPRINT CHR$(27)"#"
I
Returns eighth bit to normal