Digital Logic Design: Midterm

SOP expression consists of AND terms joined together by OR

True

POS expression consists of OR terms joined together by AND

True

Two circuits with different gate arrangements can produce the same output for every input combination

True

DeMorgan's theorem states that (AC)' = A'C'

False

Simplifying a Boolean expression can reduce the number of gates and connections required in a circuit

True

When creating an SOP expression from a truth table, an AND term is written for every row where the output is 0

False

For A = 0, B = 1, C = 1, the corresponding AND term is A'BC

True

A 4-variable Karnaugh map contains 16 squares

True

Two K-map cells are adjacent when they differ in exactly one variable

True

The left and right edges of a K-map can be adjacent

True

A K-map group may contain 3 adjacent cells

False

Larger K-map groups generally produce simpler Boolean terms

True

Variables that change within a K-map group are eliminated

True

XOR produces a HIGH output when its two inputs are at the same logic level

False

XNOR is the inverse of XOR

True

AB + A'B' represents XNOR

True

An XNOR gate can determine whether two input bits are equal

True

For an AND enable circuit, setting the control input to 1 allows the other input signal to pass to the output

True

A 74HC86 belongs to the high-speed CMOS family

True

A floating TTL input acts like logic 1

True

Unused CMOS inputs should normally be left floating

False

DIP pin numbering begins near the notch or dot and proceeds counterclockwise when viewed from the top

True

Fault isolation is the process of locating the faulty component or circuit location

True

In-system programming requires the PLD to be removed from its circuit before programming

False

In top-down design, major subsections are defined before individual circuits inside them

True

AB' + C is an SOP expression

True

In ABC + DE', ABC and DE' are the product terms

True

Multiplying out Boolean terms can help reveal common factors and possible cancellations

True

A truth-table row whose output is 0 must be included as a minterm when forming an SOP expression

False

A three-input majority function is HIGH for input combination 111

True

A three-input majority function is HIGH for input combination 100

False

A 2-variable K-map contains eight cells

False

K-map groups are allowed to overlap when doing so helps obtain a simpler expression

True

For a minimum POS form, the zeros of the function are used in the K-map process

True

In a K-map, diagonal cells are automatically adjacent

False

The XOR expression A'B + AB' is HIGH when A and B are different

True

XOR and XNOR can both be HIGH for the same two-input combination

False

A 2-bit equality detector can use one XNOR for each bit pair and an AND gate to combine the comparison results

True

For an OR enable circuit, a control input of 0 allows signal A to pass through

True

For an OR enable circuit, setting the control input to 1 forces the output LOW

False

A chip containing fewer than 12 gates is classified as SSI in the lecture

True

The 74LS prefix identifies the Low-power Schottky TTL family

True

The 74HCT series is both pin-compatible and electrically compatible with TTL

True

A voltage in the indeterminate logic range can be assumed to be a valid logic 0

False

A connection diagram can show pin numbers, component values, signal names, and power-supply voltages

True

An internally open output is guaranteed to remain LOW

False

Two internally shorted input pins can be forced to carry identical signals

True

With circuit power OFF, an ohmmeter can help confirm whether two points are shorted

True

Driving too many inputs from one output can pull the output voltage into the indeterminate range

True

A PLD design can be described using schematic diagrams, logic equations, truth tables, or HDL

True

Which expression is in SOP form?

AB + C'D

What is the main reason for simplifying a Boolean expression?

To reduce gates, wiring, cost, and delay

According to DeMorgan's theorem, (AC)' equals

A' + C'

Which Boolean law states B + B' = 1?

Complement law

For A = 0, B = 1, C = 1, which AND term represents the input combination?

A'BC

A three-input majority circuit produces HIGH when

At least two inputs are HIGH

How many squares are in a 4-variable K-map?

16

Two K-map cells are adjacent when

They differ in exactly one variable

Which is a valid K-map group size?

8

Why are larger K-map groups preferred?

They produce simpler terms

Which variables remain in the Boolean term produced by a K-map group?

Variables that remain constant within the group

When is an XOR output HIGH?

When the inputs are different

Which expression represents XOR?

A'B + AB'

Which expression represents XNOR?

AB + A'B'

Why is XNOR useful in an equality detector?

It outputs 1 when two bits are equal

Which IC is identified in the lecture as a high-speed CMOS quad XOR?

74HC86

For an AND enable circuit, which value of control input B allows A to pass to the output?

1

A chip containing 500 gates belongs to which integration category?

LSI

What identifies the starting end for numbering pins on a DIP package?

The notch or dot

What prefix identifies Low-power Schottky TTL?

74LS

According to the lecture, what does a floating TTL input act like?

Logic 1

What is the primary goal of fault isolation?

Find the exact faulty part or location

Which instrument is appropriate for checking whether a digital signal is present on a single pin?

Logic probe

What is the main advantage of in-system programming of a PLD?

The PLD can be programmed while remaining in its circuit

What should be done if simulation shows an error in a PLD design?

Return to the design, correct the error, and repeat compilation and simulation

Which of the following is a POS expression?

(A + B')(C + D)

In the SOP expression ABC + DE', which are the product terms?

ABC and DE'

Why is it useful to write a circuit's output as a Boolean expression before simplifying it?

It provides an exact logical description that Boolean rules can be applied to

Which input patterns make a 3-input majority function HIGH?

011, 101, 110, 111

What is the simplified majority expression presented in the lecture?

AB + AC + BC

How many cells are in a 2-variable K-map?

4

What is the practical K-map limit described in the lecture?

About 5 or 6 variables

Why may K-map groups overlap?

Repeating coverage does not change the function and can allow larger simplifying groups

For POS simplification, which K-map values are grouped?

The zeros

Which statement about K-map wraparound is correct?

The left and right edges can be adjacent, and the top and bottom edges can be adjacent

Which input combination makes XOR LOW?

A = 1, B = 1

Which input combination makes XNOR HIGH?

A = 0, B = 0

In a 2-bit equality detector, what combines the two XNOR outputs?

An AND gate

For an OR gate used as an enable circuit, which control value allows A to pass?

B = 0

When B = 1 in an OR enable circuit, what happens to the output?

It is forced HIGH

Which integration category covers 12 to 99 gates per chip in the lecture?

MSI

Which package has J-shaped leads that curl under the IC?

PLCC

Which CMOS series is described as high-speed and pin-compatible with TTL?

74HC

Which CMOS series is described as high-speed, pin-compatible, and electrically compatible with TTL?

74HCT

Why should a voltage in the indeterminate range be avoided?

The device may interpret it unpredictably and may draw extra current

Which chip type is identified as Z2 in the lecture's connection-diagram example?

74HC00

What happens to an IC input that is internally shorted to ground?

It is stuck LOW

What is a likely indication of an internally open output?

An unpredictable output voltage

What should be checked when a power supply may be causing erratic logic operation?

Supply voltage and AC ripple

Which sequence best matches the lecture's PLD verification flow?

Describe/design, test/compile, simulate, program, verify