Canon A-1 Repair Manual page 39

40
110
101
A will
be 011
=
3
B will
be 111
=
7
C will be 101
= 5
0
will
be 100
= 4
Fig.
11
Decection
of Cords
Depending on the movements of the wire brush, this
would lead to a completely wrong value. The gray
code was invented to surmount this type of obstacle.
The switchover of adjoining code is only one and,
therefore , even when the wire brush moves on the
boundary of code, only either one of code will be
inputted, the effective on e will appear in the
viewfinder display. Plea se notice that signals
inputted by the Gray code will be decoded into the
natural binary code in the CPU circuit. Therefore,
the Gray code assure error-proof function.
Natural Binary Code Gray Code
0 000 000
1 001
001
2
010
011
3
011
010
4 100
110
5
101 111
6
110 101
7
111 100