Design Project 1
Problem Description:
In digital computers, letters of the alphabet and the ten decimal numerals can
be coded in the form of unique combinations of five or six bits. One of these
codes is the 6-bit Flexowriter code, which is used for some punched paper
tape. A code similar to this is given below in terms of octal equivalents.
Character Codes
A
B
C
D
E
F
64
4
44
16
7
37
G
H
I
J
K
L
77
5
33
6
32
36
M
N
O
P
Q
R
24
40
71
0
12
75
S
T
U
V
W
X
41
13
51
17
55
60
Y
Z
0
1
2
3
45
73
43
63
62
2
4
5
6
7
8
9
52
66
46
22
42
72
All character codes are in Octal. To convert the octal code to its six bit
equivalent, convert each digit (octal) to its three digit binary equivalent. For
example, Z = 73 = 111 011 = 111011. To convert each octal code to its
decimal equivalent, multiply each digit by its decimal weight. For example, Z =
73 = 7x8 + 3x1 = 56 + 3 = 59.
Your job is to design a circuit which detects whether a code on six data lines
represents a number, a letter, or an illegal code. The circuit should produce
three output signals, A, N, and I, as shown below.
Interpretation
0
1
A N I
1
0
X X 1 Illegal character sensed (X = don't care)
0 Alphabetic character sensed
0 Numeric character sensed
Objective
Design a circuit that implements the expression using only 2, 3, 4, and 8 input
NAND gates and inverters. You are to use a maximum of 8 IC packages.