Control Commands
An Introduction
This section explains the following:
•
Communication basics
•
Sending control codes and control commands
•
Identifying data bytes
•
Typographic conventions
COMMUNICATION BASICS
Communication between the computer and printer is accomplished by
exchanging codes that have a predefined meaning. The building blocks
of these codes are bits and bytes.
Bits are the fundamental element of computer communication and may
have one of two values: zero and one. Computers and printers recognize
only these two states: zero and one.
A byte, or data byte, is a group of 8 bits that have significance as a unit.
There are 256 possible patterns of zeros and ones in an 8-bit data byte,
so there are 256 unique data bytes. Individual data bytes are identified by
a number related to the pattern of zeros and ones.
There are different conventions for assigning meaning to individual data
bytes. In the 4100 printer, two different conventions are used:
