ZiLOG Z8 Series

Z8
®
CPU
User Manual
UM001604-0108 Instruction Description
181
Enable Interrupts
Syntax
EI
Instruction Format
Operation
IMR (7) ← 0
Bit 7 of Control Register FBh (the Interrupt Mask Register) is set to 1. This allows poten-
tially enabled interrupts to become enabled.
Example
If Control Register FBh contains 0Ah (00001010) (interrupts IRQ1 and IRQ3 are
selected), the statement:
EI
Op Code: 9F
sets Control Register FBh to 8Ah (10001010b) and enables IRQ1 and IRQ3.
Cycles
OPC
(Hex)
OPC 6 9F
Flag Description
C Unaffected
Z Unaffected
S Unaffected
V Unaffected
D Unaffected
H Unaffected