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17-Table 7.2 Intel 8085 External Signals
Figure 7.9 gives an example of 8085 timing, showing the value of external control signals. Of course, at
the same time, the control unit generates internal control signals that control internal data transfers. The
diagram shows the instruction cycle for an OUT instruction.
Three machine cycles (M1, M2, M3) are needed. During the first, the OUT instruction is fetched. The
second machine cycle fetches the second half of the instruction, which contains the number of the I/O
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