Digital Systems for the
Electrical FE Exam

by Justin Kauwale, P.E.

Introduction

Digital Systems accounts for approximately 7 to 11 questions on the Electrical FE exam. The NCEES FE Electrical & Computer Engineering Outline covers nearly all the topics from a Digital Systems class in college. The topics range from the first part of a normal college class, which would include number systems, Boolean logic in algebraic form and gate/circuit form. Also included in the outline are flip flops, counters, programmable logic devices, gate arrays, state machine design, data controller design and timing. Even though all these topics are included in the outline, the questions will most likely revolve around the topics that are easier to test. For insight into what is easier to test, you should refer to the NCEES FE Reference Handbook.

The NCEES FE Reference Handbook section on Digital Systems is located in the Electrical and Computer Engineering section. It covers number systems, logic operations (gate/circuit form), flip flops and Karnaugh maps. You can see that many of the outline topics are not included in the handbook, which seems to indicate that the other outline topics will be less of a focus on the actual exam. This section will still discuss those topics but you should keep this discussion in mind, when reviewing those topics.



2.0 NUMBER SYSTEMS

There are three number systems that you should know for this section, (1) Decimal, (2) Binary and (3) Hexadecimal. The decimal system is the system that you often use. It uses the integers 0-9 to represent.

When converting integers to binary numbers, you should create the table below and use it as a guide. The table reads from left to right and it is all the powers of 2.

When you convert an integer to binary, you must take the largest power of 2 and then add up all the values of the powers of 2, from left to right to add up to the integer. For example, “17” is created by starting with 16 and then adding up all the values required from left to right until the sum 17 is created. In this case it is just the 4th power and the 0th power. A “1” is placed underneath all the powers that apply to this integer and a zero for all those that don’t apply.

Now try it one more time by creating “30”. Start at “16” and place a “1” underneath. Then place another “1” under “the 3rd power, this gives you 24. Then another “1” under the 2nd power, which gives you 28. Finally, another “1” under the 1st power.

Now that you understand how to complete this process manually, you should also know how to complete this process with your calculator. On the FE exam, any calculation you can complete quickly on your calculator will greatly help you to save time that can be used on more complicated questions.



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

3.0 BOOLEAN LOGIC



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

4.0 LOGIC GATES AND CIRCUITS



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

5.0 LOGIC MINIMIZATION



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

6.0 FLIP-FLOPS AND COUNTERS



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

7.0 PROGRAMMABLE LOGIC DEVICES AND GATE ARRAYS



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

8.0 STATE MACHINE DESIGN



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

9.0 DATA PATH/CONTROLLER DESIGN



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

10.0 TIMING



This section is continued in more detail in the technical study guide . Also included are many more practice exam problems.

11.0 Practice Problems

11.1 PRACTICE PROBLEM 1 –



11.2 PRACTICE PROBLEM 2 –



11.3 PRACTICE PROBLEM 3 -



Practice Problems 4 through 13 and all solutions included in the technical study guide, along with many more practice exam problems.

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