Lesson 7: Addressing Modes
From "AMERICAN LABORATORY"
by David G. Larsen, Peter R. Rony, and Jonathan A. Titus
Internal Registers within the 8080 Chip
IN THIS and several subsequent
columns, additional. details will be
given concerning the softwarecontrolled
operations of an 8080Abased
microcomputer. The software
instructions, or steps, actually indicate
to the microcomputer the tasks
it must perform. Just as one might
start the day with a list of things to
be done and a sequence of performance,
the microcomputer, too,
must be provided with a sequential
list of program steps. This is called
software.
In general, we may not be familiar
with what each microcomputer instruction
does within the microprocessor
chip. This does not deter us,
however, from using them in all of
our programs. Many of us are not
familiar with the inner workings of .
an internal combustion engine, an
automatic transmission, or a Xerox
machine; our lack of knowledge does
not prevent us from using them
daily.
Read More: Internal Registers.pdf [311KB]
Register Pair Instructions
IN THE NOVEMBER column we discussed the single-byte data transfer instructions MOV D, S and MVI >82< in the
8080 microprocessor instruction set. We summarize the significant point of the column in Figure 1, which indicates
that for MVI r >82< instruction, the data byte transferred to a register comes from the instruction itself, whereas
for the MOV D S instruction, the data byte is copied into the destination register D from the source register S.
Read More: Register Pair Instructions.pdf [1.19MB]