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INSTRUCTION SET
EI
— Enable Interrupts
EI
SYM (0) ← 1
Operation:
An EI instruction sets bit zero of the system mode register, SYM.0 to "1". This allows interrupts to
be serviced as they occur (assuming they have highest priority). If an interrupt's pending bit was set
while interrupt processing was disabled (by executing a DI instruction), it will be serviced when you
execute the EI instruction.
Flags:
No flags are affected.
Format:
opc
Example:
Given: SYM = 00H:
EI
If the SYM register contains the value 00H, that is, if interrupts are currently disabled, the statement
"EI" sets the SYM register to 01H, enabling all interrupts. (SYM.0 is the enable bit for global
interrupt processing.)
6-40
Bytes
Cycles
Opcode
1
4
S3C80A5B
(Hex)
9F
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