RCA 70/46 Reference Manual page 166

Decimal Arithmetic
Instructions
Decimal Overflow •
A decimal overflow
inter~upt
exists when the result field of an Add
Decimal, Subtract Decimal, or Zero and Add instruction is too small to
contain the overflow data. The operation is completed by ignoring the
overflow data, and setting the condition code to 3. If the decimal overflow
program mask bit is reset, interrupt will not occur and the flag in the IFR
will not be set.
Divide Error •
A divide error interrupt occurs when the quotient is greater than the
specified data field, including division by zero, or the dividend does not
have one leading zero. Division is suppressed and the dividend and divisor
remain unchanged in main memory.
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