ZiLOG Z8 Series

Z8
®
CPU
User Manual
UM001604-0108 Instruction Description
233
STOP
Syntax
STOP
Instruction Format
Operation
This instruction turns OFF the internal system clock (SCLK) and external crystal (XTAL)
oscillation, and reduces the standby current. STOP mode is terminated by a RESET which
causes the processor to restart the application program at address
000Ch.
In order to enter STOP mode, it is necessary to first flush the instruction pipeline to avoid
suspending execution in mid-instruction. You must execute a NOP immediately before the
execution of the STOP instruction.
Example
The statements:
NOP
STOP
Op Codes: FF 6F
place the Z8
®
CPU into STOP mode.
Cycles
OPC
(Hex)
OPC 6 6F
Flag Description
C Unaffected
Z Unaffected
S Unaffected
V Unaffected
D Unaffected
H Unaffected
Note: