Question

Suppose a Pep/9 simulator contains the following values Accumulator: 19AC Index Register: FE20 Memory Address [0A3F]: FF00 Memory Address [0A41]: 103D What is the value of the Index Register after the instruction C90A3F is executed?

a. FE
b. FE00
c. 20
d. FF0

Answer 1

The value of the index register after the instruction C90A3F is executed is FEA5F.

Step-by-step explanation:

The instruction C90A3F in the Pep/9 simulator is a store instruction. It stores the value from the accumulator into the memory address specified by the index and offset. The index register in this case is FE20 and the offset is 0A3F.

To calculate the memory address, you add the index register value and the offset together. So, FE20 + 0A3F = FEA5F.

Therefore, the value of the index register after the instruction C90A3F is executed is FEA5F.