MACHINE ARCHITECTURE
1. Below we give the microprogram, and a trace for the instruction
20: 1234 R2 <- R3 + R4
Step Control line Trace of 20: 1234
--------------------------------------------
0 PATH g: PC -> MAR
1 LOAD MAR 20 -> MAR
2 LOAD MRR mem[20] -> MRR
3 PATH c: MRR -> IR
4 LOAD IR 1234 -> IR
5 INCR pc pc <- 21
6 PATH f: IR -> PSe
7 PATH e: PSf -> PSd
8 PATH d: PSe -> RAR
9 LOAD RAR 3 -> RAR
10 LOAD RRR R2 -> RRR
11 PATH a: RRR -> ALU
12 WRITE ALU 1 R2 -> ALU 1
13 PATH f: IR -> PSd
14 PATH d: PSf -> RAR
15 LOAD RAR 4 -> RAR
16 LOAD RRR R2 -> RRR
17 PATH a: RRR -> ALU
18 WRITE ALU 2 R2 -> ALU 1
19 ALU ADD
20 PATH b: ALU -> RWR
21 LOAD RWR R3 + R4 -> RWR
22 PATH e: IR -> PSd
23 PATH d: PSe -> RAR
24 LOAD RAR 2 -> RAR
25 WRITE reg mem R2 <- R3 + R4