The following is a listing of the microcode that interprets the MAC-1 assembly language.
0: mar:=pc; rd;
1: pc:=pc + 1; rd;
2: ir:=mbr; if n then goto 28;
3: tir:=lshift(ir + ir); if n then goto 19;
4: tir:=lshift(tir); if n then goto 11;
5: alu:=tir; if n then goto 9;
6: mar:=ir; rd; {0000 = LODD}
7: rd;
8: ac:=mbr; goto 0;
9: mar:=ir; mbr:=ac; wr; {0001 = STOD}
10: wr; goto 0;
11: alu:=tir; if n then goto 15;
12: mar:=ir; rd; {0010 = ADDD}
13: rd;
14: ac:=mbr + ac; goto 0;
15: mar:=ir; rd; {0011 = SUBD}
16: ac:=ac + 1; rd;
17: a:=inv(mbr);
18: ac:=ac + a; goto 0;
19: tir:=lshift(tir); if n then goto 25;
20: alu:=tir; if n then goto 23;
21: alu:=ac; if n then goto 0; {0100 = JPOS}
22: pc:=band(ir,amask); goto 0;
23: alu:=ac; if z then goto 22; {0101 = JZER}
24: goto 0;
25: alu:=tir; if n then goto 27;
26: pc:=band(ir,amask); goto 0; {0110 = JUMP}
27: ac:=band(ir,amask); goto 0; {0111 = LOCO}
28: tir:=lshift(ir + ir); if n then goto 40;
29: tir:=lshift(tir); if n then goto 35;
30: alu:=tir; if n then goto 33;
31: a:=ir + sp; {1000 = LODL}
32: mar:=a; rd; goto 7;
33: a:=ir + sp; {1001 = STOL}
34: mar:=a; mbr:=ac; wr; goto 10;
35: alu:=tir; if n then goto 38;
36: a:=ir + sp; {1010 = ADDL}
37: mar:=a; rd; goto 13;
38: a:=ir + sp; {1011 = SUBL}
39: mar:=a; rd; goto 16 ;
40: tir:=lshift(tir); if n then goto 46;
41: alu:=tir; if n then goto 44;
42: alu:=ac; if n then goto 22; {1100 = JNEG}
43: goto 0;
44: alu:=ac; if z then goto 0; {1101 = JNZE}
45: pc:=band(ir,amask); goto 0;
46: tir:=lshift(tir); if n then goto 50;
47: sp:=sp + (-1); {1110 = CALL}
48: mar:=sp; mbr:=pc; wr;
49: pc:=band(ir,amask); wr; goto 0;
50: tir:=lshift(tir); if n then goto 65;
51: tir:=lshift(tir); if n then goto 59;
52: alu:=tir; if n then goto 56;
53: mar:=ac; rd; {1111-0000 = PSHI}
54: sp:=sp + (-1); rd;
55: mar:=sp; wr; goto 10;
56: mar:=sp; sp:=sp + 1; rd; {1111-0010 = POPI}
57: rd;
58: mar:=ac; wr; goto 10;
59: alu:=tir; if n then goto 62;
60: sp:=sp + (-1); {1111-0100 = PUSH}
61: mar:=sp; mbr:=ac; wr; goto 10;
62: mar:=sp; sp:=sp + 1; rd; {1111-0110 = POP}
63: rd;
64: ac:=mbr; goto 0;
65: tir:=lshift(tir); if n then goto 73;
66: alu:=tir; if n then goto 70;
67: mar:=sp; sp:=sp + 1; rd; {1111-1000 = RETN}
68: rd;
69: pc:=mbr; goto 0;
70: a:=ac; {1111-1010 = SWAP}
71: ac:=sp;
72: sp:=a; goto 0;
73: tir:=lshift(tir); if n then goto 76;
74: a:=band(ir,smask); {1111-1100 = INSP}
75: sp:=sp + a; goto 0;
76: alu:=tir; if n then goto 80;
77: a:=band(ir, smask); {1111-1110 = DESP}
78: a:=inv(a);
79: a:=a + 1; goto 75;
80: halt; {1111-1111 = HALT}