The hypothetical machine has two I/O instructions: 0011= Load AC fro I/O 0111= Store AC to I/O Solutions

Problem Set :

The hypothetical machine of figure 3.4 also has two I/O instructions:
0011= Load AC fro I/O
0111= Store AC to I/O
In these cases the 12-bit address identifies a particular I/O device. Show the program execution (using format of figure 3.5) for the following program:
1. Load AC from device 5.
2. Add contents of memory location 940.
3. Store AC to device 6.
Assume that the next value received from device 5 is 3 and that location 940 contains value of 2.

Solution:

Figure (Say)

We will assume that the memory (contents in hex) as the previous table:
300: 3005; 301: 5940; 302: 7006
Therefore, the steps will be as the following:
Step 1: 3005 → IR
Step 2: 3 → AC
Step 3: 5940 → IR
Step 4: 3 + 2 = 5 → AC
Step 5: 7006 → IR
Step 6: AC → Device 6