Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations - Manual (Page 30)

Chapter
4
4Ć1
Memory Organization
This chapter describes:
Hardware and its relationship to your program
Memory and its components
In chapter 2 we described in general terms the processor’s memory section.
Now we want to give you detailed concepts of the memory’s organization and
its structure. Understanding these concepts will aid you in programming your
processor.
Before we explain memory organization and its structure, there are some
vocabulary definitions that will clarify this chapter:
Bit: the smallest unit of information that memory is capable of retaining.
Byte: a group of 8 bits.
Word: a group of 16 bits.
Hardware vs. Your Program
The chart below and Figure 4.1 represent how the hardware of your system
relates to the input and output image tables. Understanding these two
illustrations will further your programming abilities.
Objectives
Introduction