HP 61010A Owner's Manual page 50

How Statements
Control the
Digital I/O
Before using any of the statements in this chapter, take
some time to review Figure 5-1. This block diagram
illustrates the relationship between the programming
statements that are discussed in this chapter and the
functions of the Digital I/O. Because some of the data
formatting is done with software and not in hardware, the
statements that are implemented by software are
surrounded by a dotted block to distinguish them from the
statements that control the hardware.
From the diagram you can identify the two primary
functions of the Digital I/O (i.e. Digital Input and Digital
I - DIGITAL INPUT
0 - DIGITAL OUTPUT
Figure 5-1. How Statements Control the Digital I/O
5*2 Programming With BASIC