Module 13 - Introduction to Number Systems and Logic
Pages i - ix,
1-1 to 1-10,
1-11 to 1-20,
1-21 to 1-33,
1-31 to 1-40,
1-41 to 1-50,
1-51 to 1-60,
1-61 to 69,
2-1 to 2-10, 2-11 to 2-20,
2-21 to 2-30,
2-31 to 2-36,
3-1 to 3-10,
3-11 to 2-20,
3-21 to 3-30,
3-31 to 3-40,
3-41 to 3-46, Index
In this case, the higher order group is invalid, but the lower order group is valid. Therefore, the correction
factor is added only to the higher order group as shown:
Convert this total to decimal to check your answer:
Remember that the correction factor is added only to groups that exceed 910 (1001BCD).
Convert the following numbers to BCD and add:
Now that you've completed this chapter, you should have a basic understanding of number systems. The number
systems that were dealt with are used extensively in the microprocessor and computer fields. The following is a
summary of the emphasized terms and points found in the "Number Systems" chapter.
The UNIT represents a single object.
A NUMBER is a symbol
used to represent one or more units.
The RADIX is the base of a positional number system.
It is equal to the number of symbols used in that number system.
A POSITIONAL NOTATION
is a system in which the value or magnitude of a number is defined not only by its digits or symbol value, but
also by its position. Each position represents a power of the radix, or base, and is ranked in ascending or
The MOST SIGNIFICANT DIGIT (MSD) is a digit within a number (whole or fractional) that has the
largest effect (weighing power) on that number.
The LEAST SIGNIFICANT DIGIT (LSD) is a digit within a number (whole or fractional) that has
the least effect (weighting power) on that number.
The BINARY NUMBER SYSTEM is a base 2 system. The symbols 1 and 0 can be used to represent the
state of electrical/electronic devices. A binary 1 may indicate the device is active; a 0 may indicate the device
The OCTAL NUMBER SYSTEM is a base 8 system and is quite useful as a tool in the conversion of
binary numbers. This system works because 8 is an integral power of 2; that is, 23 = 8. The use of octal
numbers reduces the number of digits required to represent the binary equivalent of a decimal number.
The HEX NUMBER SYSTEM is a base 16 system and is sometimes used in computer systems. A binary
number can be converted directly to a base 16 number if the binary number is first broken into groups of four
The basic rules of ADDITION apply to each of the number systems. Each system becomes unique when
carries are produced.
SUBTRACTION in each system is based on certain rules of that number
system. The borrow varies in magnitude according to the number system in use. In most computers, subtraction is
accomplished by using the complement (R's or R's-1) of the subtrahend and adding it to the minuend.
CONVERT A WHOLE BASE 10 NUMBER to another system, divide the decimal number by the base of the number
system to which you are converting. Continue dividing the quotient of the previous division until it can no longer
be done. Extract the remainders - the remainder from the first computation will yield the LSD; the last will
provide the MSD.
To CONVERT DECIMAL FRACTIONS, multiply the fraction by the base of the desired number system.
Extract those digits that move to the left of the radix point. Continue to multiply the fractional product for as
many places as needed. The first digit left of the radix point will be the MSD, and the last will be the LSD. The
example to the right shows the process of converting 248.3210 to the octal equivalent (370.2438).
BINARY numbers are converted to OCTAL and HEX by the
grouping method. Three binary digits equal one octal digit; four binary digits equal one hex digit.
To CONVERT binary, octal, and hex numbers to DECIMAL use the POWERS of the base being
BINARY-CODED DECIMAL (BCD) is a coding system used with some microprocessors. A correction
factor is needed to correct invalid numbers
ANSWERS TO QUESTIONS Q1. THROUGH Q110.
A4. The number of symbols used in the system
A6. 103, 102, 101, 100
A7. Radix point
(a) MSD - 4, LSD - 0
(b) MSD - 1, LSD - 6
MSD - 2, LSD - 4
(d) MSD - 2, LSD - 1
A88. 110112; 338
A90. 1000101.1012; 105.58
A109. 0001 0001BCD
A110. 0010 0010BCD
NEETS Table of Contents
- Introduction to Matter, Energy,
and Direct Current
- Introduction to Alternating Current and Transformers
- Introduction to Circuit Protection,
Control, and Measurement
- Introduction to Electrical Conductors, Wiring
Techniques, and Schematic Reading
- Introduction to Generators and Motors
- Introduction to Electronic Emission, Tubes,
and Power Supplies
- Introduction to Solid-State Devices and
- Introduction to Amplifiers
- Introduction to Wave-Generation and Wave-Shaping
- Introduction to Wave Propagation, Transmission
Lines, and Antennas
- Microwave Principles
- Modulation Principles
- Introduction to Number Systems and Logic Circuits
- Introduction to Microelectronics
- Principles of Synchros, Servos, and Gyros
- Introduction to Test Equipment
- Radio-Frequency Communications Principles
- Radar Principles
- The Technician's Handbook, Master Glossary
- Test Methods and Practices
- Introduction to Digital Computers
- Magnetic Recording
- Introduction to Fiber Optics