Siemens C500 User Manual page 23

ALE
a) 1 Byte, 1-Cycle Instruction, e.g. INC A
b) 2 Byte, 1-Cycle Instruction, e.g. ADD A, #Data
c) 1 Byte, 2-Cycle Instruction, e.g. INC DPTR
d) MOVX (1 Byte, 2-Cycle)
Figure 3-1
Fetch Execute Sequence
Semiconductor Group
S1 S2 S3 S4
P1 P2 P1 P2 P1 P2 P1 P2
Read Read next
Opcode Opcode (Discard)
S1 S2 S3 S4
Read Read 2nd
Opcode Byte
S1 S2 S3 S4
Read
Opcode
S1 S2 S3 S4
Read Read next
Opcode Opcode
(MOVX) (Discard)
S1 S2 S3 S4
S5 S6 S1 S2
P1 P2 P1 P2 P1 P2 P1 P2 P1
S5 S6
S5 S6
Read next Opcode again
Read next Opcode (Discard)
S5 S6 S1 S2
Read next Opcode again
No Fetch
No ALE
S5 S6 S1 S2
ADDR DATA
Access of External Memory
3-2
CPU Timing
C500 Family
S3 S4 S5 S6
P2 P1 P2 P1 P2 P1 P2
Read next
Opcode again
Read next
Opcode
S3 S4 S5 S6
No Fetch
S3 S4 S5 S6
MCD02771
1998-04-01