Epson 4100 manual Control Commands An Introduction, Communication Basics

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: