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By using a logical instruction and a mask, individual bits within registers can be accessed for bit set, bit clear,
bit complement, or bit test operations. For example, the instruction AND R15, MASK performs a bit clear
operation. Figure 1-3 shows this example.
0
1
AND R15, DFH
0
When instructions are executed, registers are only read, not written, when defined as sources; and read and/or
written when defined as destinations. All General-Purpose Registers function as accumulators, address
pointers, index registers, stack areas, or scratch pad memory.
General-Purpose Registers
General-Purpose Registers (GPR) are undefined after the device is powered up. The registers keep their last
value after any reset, as long as the reset occurs in the V
its last state from a V
LV
Figure 1-2. 16-Bit Register Addressing
1
1
1
1
0
1
1
0
1
Figure 1-3. Accessing Individual Bits (Example)
reset if V
drops below 1.8V.
CC
MSB
LSB
Rn
Rn+1
n = Even
Address
0
0
1
1
;Clear Bit 5 of Working Register 15
0
0
voltage-specified operating range. It does not keep
CC
0
0
R15
1
1
MASK
0
0
R15
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