MA2901
Octal
Group
I
5,4,3
/I
2,1,0
40
41
45
46
30
31
35
36
60
61
65
66
70
71
75
76
72
73
74
77
62
63
64
67
32
33
34
37
40
43
44
47
50
51
55
56
Function
A
Λ
Q
A
Λ
B
D
Λ
A
D
Λ
Q
A
V
Q
A
V
B
D
V
A
D
V
Q
A
∇
Q
A
∇
B
D
∇
A
D
∇
Q
AN
∇
QN
AN
∇
BN
DN
∇
AN
DN
∇
QN
Q
B
A
D
Q
B
A
D
Q
B
A
D
0
0
0
0
AN
Λ
Q
AN
Λ
B
DN
Λ
A
DN
Λ
Q
AND
OR
EX-OR
EX-NOR
INVERT
PASS
PASS
‘ZERO’
AND
+ = plus; - = minus;
V
= OR;
Λ
= AND;
∇
= EX-OR
Figure 6: ALU Logic Mode Functions (C
n
Irrelevant)
Octal
I
5,4,3
/I
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
Group
Cn=0(Low)
Function
A+Q
A+B
D+A
D+Q
Q
B
A
D
Q-1
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
Cn = 1 (High)
Group
ADD
plus one
Function
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
PASS
Increment
Decrement
PASS
1s comp
2s comp
(negate)
SUBTRACT
(1s comp)
SUBTRACT
(2s comp)
Figure 7: ALU Arithmetic Mode Functions
5
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