C517A_99 Datasheet, PDF (26/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Fundamental Structure
C517A
OSC
(XTAL1)
S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6
P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2 P1 P2
ALE
Read
Opcode
Read next
Opcode (Discard)
Read next
Opcode again
S1 S2 S3 S4 S5 S6
a) 1-Byte,
1-Cycle Instruction, e.g. INC A
Read
Opcode
Read 2nd
Byte
S1 S2 S3 S4 S5 S6
Read next
Opcode
b) 2-Byte,
1-Cycle Instruction, e.g. ADD A,
# Data
Read
Opcode
Read next Opcode again
Read next Opcode (Discard)
c) 1-Byte,
S1 S2 S3 S4 S5 S6
2-Cycle Instruction, e.g. INC DPTR
Read
Opcode
(MOVX)
Read next
Opcode
(Discard)
S1 S2 S3 S4 S5 S6
Read next Opcode again
No Fetch
No ALE
No Fetch
S1 S2 S3 S4 S5 S6 S1 S2 S3 S4 S5 S6
d) MOVX (1-Byte, 2-Cycle)
ADDR
DATA
Access External Memory
MCD03218
Figure 2-2
Fetch Execute Sequence
Semiconductor Group
2-6