DS80C320-MCG Datasheet, PDF (75/175 Pages) Dallas Semiconductor – High-Speed Microcontroller User Guide

High-Speed Microcontroller User’s Guide
Table 5-2 provides a summary by instruction type. Note that many of the instructions provide multiple
opcodes. As an example, the ADD A, Rn instruction can act on one of 8 working registers. There are 8
opcodes for this instruction because it can be used on 8 independent locations. Table 5-2 shows totals for
both number of instructions and number of opcodes. Averages are provided in the tables. However, the
real speed improvement seen in any system will depend on the instruction mix. Programs that use
immediate or direct data combined with the accumulator or working registers will be improved the least.
These are two cycle, two byte instructions. Moderate performance improvement will be gained by
emphasizing short branches and instructions that use only direct and immediate data (no accumulator or
working register). These instructions tend to be three cycle instructions. The largest number of
improvements come from the single cycle instructions involving only the accumulator and working
registers. Also, the two cycle data movement instructions involving the working registers are greatly
improved.
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