Suppose the hypothetical processor of Figure 1.3 also has two I/O instructions:

0011 = Load AC from I/O

0111 = Store AC to I/O

In these cases, the 12-bit address identifies a particular external device. Show the program execution (using format of Figure 1.4) 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 retrieved from device 5 is 3 and that location 940 contains a value of 2.

Fetch stage Execute stage CPU registers Memory CPU registers emo 3001 9 4 0 301 5 9 4 0 3 0 0 PC 300 1 9 4 0 AC 3015 9 4 1 3 0 1 PC 0 0 0 3 AC 940 10 0 0 3 941 0 0 0 2 Step 1 940 10 0 0 3 941 0 0 0 2 Step 2 emo CPU registers Memory CPU registers 300 1 9 4 0 301 5 9 4 1 302 3 0 IPC 3001 9 4 0 () 0 0 3|AC| 301 | 5 9 4 1 5941 IR 302 2 9 4 I 2 3 0 2 PC 0 0 0 5 AC 59411R 940 0 0 0 3 941 0 0 0 2 940 0 0 0 3 94110 0 0 2 Step 4 Memory 300 1 9 4 0 301 5 9 4 1 302 2 9 4 1 CPU registers CPU registers 3 0 3 PC Memory 3 0 2 PC 300 1 9 4 0 0 0 0 5 AC301 5 9 4 1 294 IR 302 29 4 1 3 940 0 0 0 3 940 0 0 0 3 941 0 0 0 2 5 941 0 0 0