MA2901
Octal
Group
AND
OR
Function
I
/I
5,4,3 2,1,0
40
41
45
46
30
31
35
36
A L Q
A L B
D L A
D L Q
A
A
D
D
Q
B
A
Q
V
V
V
V
60
61
65
66
70
71
75
76
72
73
74
77
A Ñ Q
A Ñ B
D Ñ A
EX-OR
EX-NOR
INVERT
DÑ Q
ANÑ QN
ANÑ BN
DNÑ AN
DNÑ QN
Q
B
A
D
62
63
64
67
32
33
34
37
40
43
44
47
50
51
55
56
Q
B
A
D
Q
B
A
D
0
0
0
0
PASS
PASS
‘ZERO’
AND
ANL Q
ANL B
DNL A
DNL Q
+ = plus; - = minus; = OR; L = AND; Ñ = EX-OR
V
Figure 6: ALU Logic Mode Functions (Cn Irrelevant)
Octal
Cn=0(Low)
Function
Cn = 1 (High)
Function
I
/I
Group
Group
5,4,3 2,1,0
00
01
05
06
02
03
04
07
12
13
14
27
22
23
24
17
10
11
15
16
20
21
25
26
A + Q
A + B
D + A
D + Q
Q
B
A
D
Q - 1
A + Q +1
A + B +1
D + A +1
D + Q + 1
Q +1
B + 1
A + 1
D + 1
Q
B
A
D
- Q
- B
- A
- D
Q - A
B - A
A - D
Q - D
A - Q
A - B
D - A
D - Q
ADD
plus one
ADD
PASS
Decrement
1s comp
Increment
PASS
B - 1
A - 1
D - 1
- Q - 1
- B - 1
- A - 1
- D - 1
Q - A -1
B - A-1
A - D-1
Q - D-1
A - Q-1
A - B-1
D - A-1
D - Q-1
2s comp
(negate)
SUBTRACT
(1s comp)
SUBTRACT
(2s comp)
Figure 7: ALU Arithmetic Mode Functions
5
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