Service manual

STP 11-25R13-SM-TG
Q - 16
binary readouts are displayed on a light panel. As a technician performing maintenance tests, you may
have to compare a binary readout to an octal reference.
(2) The base of the octal number system is 8, which means that only eight symbols are used. The
symbols are 0, 1, 2, 3, 4, 5, 6, and 7. The place value of each octal digit is expressed in powers of eight
as shown here.
8
10
8
9
8
8
8
7
8
6
8
5
8
4
8
3
8
2
8
1
8
0
(3) Octal counting proceeds from 0 to 7 just as in decimal. However, at 7 in the octal system there
are no more, symbols available. To progress from 7 to the next count, a carry operation similar to that
used to progress from 9 to 10 in decimal is required. We would progress from octal 7 to octal 10. The
second digit, 1, has a place value of 8 to the first power, which is equivalent to decimal 8. Thus, octal 10
equals decimal 8.
(4) A comparison between decimal, binary, and octal numbers is shown in Table Q-10.
Table Q-10. Relationship of Decimal, Binary, and Octal Numbers
(5) Note the relationship between decimal, binary, and octal. Keep in mind that powers of two are
used in binary and powers of eight in octal. Studying the count from 0 to 7 reveals that any three-bit
binary number can be written in octal using just one digit. Also, maximum count for three places in binary
(111
2
) is equal to the maximum count for one place in octal.
Decimal Binary Hexadecimal
0 = 000 = 0
1 = 001 = 1
2 = 010 = 2
3 = 011 = 3
4 = 100 = 4
5 = 101 = 5
6 = 110 = 6
7 = 111 = 7
8 = 1000 = 10
9 = 1001 = 11