Digital Electronics – Second Semester Exam Name:______

MSB / LSB
/ Create a State Machine that will count out powers of 2. So that you have a nice number of states to work with, we will have a zero displayed first.
·  Think of this as two separate state machines intertwined and operating simultaneously, one for each digit.
·  You may use your notes, old projects, and anything you find online. You may not use each other or me. I will only assist with computer problems, not logic problems.
·  Answer the questions below.
·  Show all work. Even though there are spots for K-Maps, you may choose between Boolean Algebra and K-Maps for simplification.
·  Use programmable logic. If you have time, download it to the DLB for bonus points.
·  Save your Multisim file to the proper place in the hsstudentsshare folder instead of printing.
1.  How many states are there? ______
2.  How many flip-flops will you need? ______
3.  How did you know what the answer to #2 would be?
4.  How many output variables will be needed for the MSB? ______
5.  How many output variables will be needed for the LSB? ______
6.  How did you know the answers to #4 and #5?

7.  Complete the State Transition Table. (To save time, I skipped having you make a State Graph.)

Inputs / Next State / MSB / LSB
Qa / Qb / Qc / EN / Next / Qa* / Qb* / Qc* / M3 / M2 / M1 / M0 / L3 / L2 / L1 / L0
S0
S0
S1
S1
S2
S2
S3
S3
S4
S4
S5
S5
S6
S6
S7
S7

8.  If you choose to use K-Maps to simplify the logic expressions, there are blank K-Maps on the next page. No matter whether you use K-Maps or Boolean Algebra, show all work, and write your FINAL simplified logic expressions here.

Qa* = ______

Qb* = ______

Qc* = ______

M3 = ______

M2 = ______

M1 = ______

M0 = ______

L3 = ______

L2 = ______

L1 = ______

L0 = ______

Qa* / QcEn / QcEn’ / Qc’En’ / Qc’En
QaQb
QaQb’
Qa’Qb’
Qa’Qb
Qb* / QcEn / QcEn’ / Qc’En’ / Qc’En
QaQb
QaQb’
Qa’Qb’
Qa’Qb
Qc* / QcEn / QcEn’ / Qc’En’ / Qc’En
QaQb
QaQb’
Qa’Qb’
Qa’Qb
M3 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
M2 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
M1 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
M0 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
L3 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
L2 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
L1 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb
L0 / Qc / Qc’
QaQb
QaQb’
Qa’Qb’
Qa’Qb