A.4
Number of States Required for Instruction Execution
The tables in this section can be used to calculate the number of states required for instruction
execution by the CPU. Table A-5 indicates the number of instruction fetch, data read/write, and
other cycles occurring in each instruction. Table A-4 indicates the number of states required for
each cycle. The number of states required for execution of an instruction can be calculated from
these two tables as follows:
Execution states = I × S
Examples: Advanced mode, program code and stack located in external memory, on-chip
supporting modules accessed in two states with 8-bit bus width, external devices accessed in three
states with one wait state and 16-bit bus width.
1. BSET #0, @FFFFC7:8
From table A-5:
I = L = 2, J = K = M = N = 0
From table A-4:
S
= 4, S
= 2
I
L
Number of states required for execution = 2 × 4 + 2 × 2 = 12
2. JSR @@30
From table A-5:
I = J = K = 2, L = M = N = 0
From table A-4:
S
= S
= S
= 4
I
J
K
Number of states required for execution = 2 × 4 + 2 × 4 + 2 × 4 = 24
1150
+ J × S
+ K × S
+ L × S
I
J
K
+ M × S
+ N × S
L
M
N