Page 135 - Understanding Automotive Electronics

2735 | CH 4 Page 122 Tuesday, March 10, 1998 11:06 AM

4 MICROCOMPUTER INSTRUMENTATION AND CONTROL

Figure 4.14
Types of Shift
Operations

FPO

Table 4.1c. Since the AND affects the accumulator and memory, values must
be put into the accumulator to be ANDed. This requires the load accumulator
instruction, LDA.
The programmer often The assembly language program of Figure 4.15 performs the required
uses special names AND function. The programmer must first know which memory location the
(labels) to refer to spe- digital buffer interface (Figure 4.12) occupies. This location is identified, and
cific memory locations. the programmer writes instructions in the assembler program so that the
buffer memory location will be referred to by the label or name SEAT. SEAT
is easier for the programmer to remember and write than the address of the
buffer.

122 UNDERSTANDING AUTOMOTIVE ELECTRONICS