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SBRK
Subtract Short-Immediate Value From Auxiliary Register
7-154
Syntax SBRK #
k
Short immediate addressing
Operands k: 8-bit positive short immediate value
SBRK #
k
1514131211109876543210
0
1111100 k
Execution Increment PC, then ...
(current AR) – k → current AR
Note that k is an 8-bit positive constant.
Status Bits None
Description The 8-bit immediate value is subtracted, right justified, from the content of the
current auxiliary register (the one pointed to by the ARP) and the result re-
places the contents of the auxiliary register. The subtraction takes place in the
auxiliary register arithmetic unit (ARAU), with the immediate value treated as
an 8-bit positive integer. All arithmetic operations on the auxiliary registers are
unsigned.
Words 1
Cycles for a Single SBRK Instruction
ROM
DARAM SARAM External
1 1 1 1+p
Example SBRK #0FFh
Before Instruction After Instruction
ARP 7 ARP 7
AR7 0h AR7 FF01h
Opcode
Cycles