Destination (base 10) - Source(base 10) -->; Destination
ABCD Dx, Dy
ABCD -(Ax), -(Ay)
Attributes: Size = (Byte)
Description: Subtracts the source operand from the destination
operand and stores the result in the destination location.
The subtraction is performed using binary coded decimal
arithmetic. The operands, which are packed BCD numbers,
can be addressed in two different ways:
1. Data register to data register (Data Register Direct).
2. Memory to memory (Pre-decrement).
This operation is a byte operation only.
X Set the same as the carry bit.
Z Cleared if the result is nonzero. Unchanged otherwise.
C Set if a decimal carry was generated. Cleared otherwise.
Note: Normally the Z condition code bit is set via programming before
the start of an operation. This allows successful tests for zero results
upon completion of multiple-precision operations.