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CHAPTER
7
SPECIAL FEATURES
OF
THE PRINTER
Subjects we'll cover in Chapter 7 include-
* Printer's bell;
l
Master reset;
l
Uni-directional printing;
l
International character sets;
l
Printing BIG characters;
l
The optional sheet feeder;
l
Reading a hex dump.
In the previous
chapters
we have learned
about
several
groups of control codes. In this chapter we will look at more con-
trol codes. These codes don't fit neatly into any of the groupings
that we have studied, but they add a lot of capability to your
printer. So here goes.
n Now hear this
You may have heard the printer's bell if you have ever run out
of paper. And you may have wondered
why it's called a bell
when it beeps instead of ringing! It's a long story that goes back
to the early days of computers,
when teletype machines were us-
ed for computer terminals. These mechanical marvels had a bell
in them that could be heard for blocks. This bell was used to
signal the operator that somethings
needed attention.
The code
that the computer
sent to the teletype machine to ring the bell
was, reasonably
enough, called a bell code. Well the name bell
code is still with us, even if the bell has changed to a beeper, and
a lot of people still call the beeper a bell, even if it doesn't sound
like one. So with our trivia lesson out of the way, let's see how
we can '"ring the bell".
The code to sound the "bell" is CHR$(7), which is ASCII code
7 or (BEL).
Any time your printer receives this code it will
sound the bell for a quarter of a second. This can be used to re-
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