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SETUSRP mn     Enter User Interrupt     Rabbit 4000/5000 Instruction

Opcode	Instruction	Operation
ED B5 n m	SETUSRP mn	SU = {SU[7:2],01} (SP - 1) = m (SP - 2) = n SP = SP - 2

Clocks	8-Bit Access	16-Bit Unaligned	16-Bit Aligned
Rabbit 4000	15	n/a	n/a
Rabbit 5000	16	14	12

Flags				ALTD			IOI/IOE
S	Z	L/V	C	F	R	SP	S	D
-	-	-	-

Description

Sets the current processor mode by setting SU bit 1 to zero and bit 0 to one.

The System/User Mode Register, SU, is an 8-bit register that forms a stack of the current processor mode and the previous 3 modes.

This instruction is used to handle user mode interrupts in system/user mode.

This is a chained-atomic instruction, meaning that an interrupt cannot take place between this instruction and the instruction following it.