Question 1

Memory sizing shorthand: In computer memory contexts, what value does 4k most commonly represent?

Accepted Answer

Introduction / Context: In computing, the letter k traditionally denotes 1024 (2^10) rather than the SI value 1000, especially for memory sizes and addressable units. As a result, 4k in memory discussions typically means 4096 bytes or addresses. Given Data / Assumptions: Context is digital memory sizing (RAM pages, blocks, buffers). Binary-based scaling is standard in many legacy and low-level contexts. We follow the power-of-two convention used in operating systems and hardware. Concept / Approach: Since 1k = 2^10 = 1024, multiply by 4: 4k = 4 * 1024 = 4096. This aligns with common page sizes (e.g., 4kB pages) and buffer alignment boundaries in systems programming. Step-by-Step Solution: Note definition: 1k (binary) = 1024.Compute 4 * 1024 = 4096.Therefore, 4k = 4096 (typically bytes). Verification / Alternative check: Typical OS page size on many architectures is 4kB, confirming 4k = 4096 bytes in practice. Why Other Options Are Wrong: 4000 is SI-based but not the standard in this legacy memory context. 40 and 400 are unrelated magnitudes. Common Pitfalls: Confusing binary k (1024) with metric k (1000); modern documentation sometimes distinguishes with KiB (kibibyte) to avoid ambiguity. Final Answer: 4096

Question 2

Digital IC technology preferences: Bipolar technology is traditionally preferred for which integration scales, while MOS is better for LSI?

Accepted Answer

Introduction / Context: Historically, bipolar transistor technologies (e.g., TTL, ECL) offered high speed and strong drive, making them suitable for small- and medium-scale integration (SSI/MSI). Metal-oxide-semiconductor (MOS) technologies excel at very high transistor densities, making them the dominant choice for large-scale integration (LSI/VLSI). Given Data / Assumptions: SSI (small-scale) and MSI (medium-scale) involve relatively few gates per chip. LSI/VLSI integrate thousands to millions of transistors. We compare typical historical preferences, not niche exceptions. Concept / Approach: Bipolar devices switch quickly and drive loads well but consume more power and scale poorly in density compared to MOS. MOSFET processes permit compact, low-power gates suitable for massive integration, the basis of modern microprocessors and memory chips. Step-by-Step Solution: Match bipolar strengths (speed/drive) to SSI/MSI.Match MOS strengths (density/low power) to LSI/VLSI.Therefore, choose “SSI, MSI” for bipolar, with MOS better for LSI. Verification / Alternative check: The transition from TTL/ECL logic families to CMOS for high-integration ICs in the 1980s–1990s reflects this preference shift. Why Other Options Are Wrong: “MSI, LSI” mixes scales and contradicts the density advantage of MOS. “SSI, LSI” splits scales inconsistently. “ECL, DTL” lists families, not integration scales. Common Pitfalls: Assuming “faster” always means “better”; for large chips, power and density dominate over raw switching speed. Final Answer: SSI, MSI

Question 3

MOSFET vs. bipolar in integrated circuits: What is the principal advantage of using MOS technology over bipolar circuitry for large ICs?

Accepted Answer

Introduction / Context: Choosing a device technology affects density, power, and cost. MOSFET-based integrated circuits, especially CMOS, enable extremely high transistor counts with low static power, making them ideal for large-scale and very-large-scale integration (LSI/VLSI). Historically, this has been the decisive advantage over bipolar logic families for large chips. Given Data / Assumptions: We are comparing mainstream advantages in IC manufacturing. “Complexity” here means achievable transistor count per chip (density). Bipolar circuits tend to consume more static power and scale poorly in density. Concept / Approach: MOS processes permit tiny, low-leakage transistors and complementary logic (CMOS) with near-zero static power, enabling dense logic with acceptable thermal profiles. Consequently, designers can implement much greater functional complexity on a single die at better cost per function than with bipolar processes for large designs. Step-by-Step Solution: Identify the core differentiator: density and static power.Relate density to achievable complexity and cost per function.Conclude that MOS's advantage is supporting much greater complexity → better economy. Verification / Alternative check: The universal adoption of CMOS for microprocessors, SoCs, and memory underscores MOS's density/cost advantages, even though bipolar (e.g., ECL) may offer higher raw speed in niche cases. Why Other Options Are Wrong: Higher operating speed (b) is generally a bipolar advantage, not MOS's. Fewer supply connections (c) is not the fundamental driver. Familiarity (d) is not a technology advantage. (e) restates the density/power idea but the keyed correct choice in this item is the complexity/economy phrasing. Common Pitfalls: Equating “faster” with “better” for all contexts; for LSI/VLSI, power and density win. Final Answer: much greater complexity (more components) than bipolar circuits : better economy

Question 4

Decimal to octal conversion: What is the octal (base 8) equivalent of the decimal number 42₁₀?

Accepted Answer

Introduction / Context: Number base conversion is a foundational skill in digital systems. Converting decimal to octal can be accomplished using repeated division by 8, collecting remainders that become the octal digits (least significant first). Given Data / Assumptions: Given: 42 in base 10. Wanted: representation in base 8. Use integer division and remainder arithmetic. Concept / Approach: The value of a number in base 8 is the sum of digits times powers of 8. Repeated division by 8 yields remainders in 0–7 which form the octal digits from right to left, ensuring correct place-value reconstruction. Step-by-Step Solution: 42 ÷ 8 = 5 remainder 2 → least significant digit = 2.5 ÷ 8 = 0 remainder 5 → next digit = 5 (stop since quotient is 0).Read upwards: 5 2 → 52₈ (written as 528). Verification / Alternative check: Check: 5*8 + 2 = 40 + 2 = 42, confirming the correctness of 52₈. Why Other Options Are Wrong: 57₈ = 47₁₀; 42₈ = 34₁₀; 47₈ = 39₁₀. Only 52₈ equals 42₁₀. Common Pitfalls: Writing digits in the wrong order (top-to-bottom instead of bottom-to-top) or mixing up quotient and remainder. Final Answer: 528

Question 5

Binary to octal conversion: Convert the binary number 11111₂ to its octal (base 8) representation.

Accepted Answer

Introduction / Context: Octal is convenient for grouping binary because 8 = 2^3, so each octal digit corresponds to three binary bits. Converting binary to octal is done by grouping bits into triples from the right and translating each group. Given Data / Assumptions: Binary input: 11111₂ (five bits). Target: base-8 representation. Leading zeros may be added to complete a leftmost group of three. Concept / Approach: Pad the left side with zeros to a multiple of three bits, then convert each 3-bit group to its octal digit using the mapping: 000→0 … 111→7. Concatenate the digits in order from most significant group to least. Step-by-Step Solution: Pad: 11111₂ → 011 111₂.Convert 011₂ → 3₈.Convert 111₂ → 7₈.Combine: 37₈ (written as 378). Verification / Alternative check: Decimal cross-check: 11111₂ = 31₁₀. 37₈ = 3*8 + 7 = 24 + 7 = 31₁₀. Both agree. Why Other Options Are Wrong: 35₈ = 29₁₀; 32₈ = 26₁₀; 42₈ = 34₁₀. Only 37₈ equals 31₁₀. Common Pitfalls: Grouping from the left instead of the right without padding; misreading 111₂ as 6 instead of 7. Final Answer: 378

Question 6

One’s complement operation: What is the 1’s complement of the binary number 11010₂?

Accepted Answer

Introduction / Context: One’s complement is a bitwise inversion operation used in certain number representations and checksums. It flips every bit: 1 becomes 0 and 0 becomes 1. Understanding this simple transform helps with error detection logic and legacy signed representations. Given Data / Assumptions: Input: 11010₂. Operation: 1’s complement (bitwise NOT). All bits are inverted independently. Concept / Approach: Apply NOT to each bit position: for a sequence bₙ…b₂ b₁ b₀, produce (~bₙ)…(~b₀). There is no carry or arithmetic—just inversion of each bit value. Step-by-Step Solution: Start: 1 1 0 1 0.Invert each bit: 0 0 1 0 1.Result: 00101₂. Verification / Alternative check: Check by re-inverting: NOT(00101₂) = 11010₂, confirming correctness. Why Other Options Are Wrong: 00010 and 00110 represent partial inversions. 11101 is unrelated; it is not the bitwise inverse of 11010. Common Pitfalls: Confusing 1’s complement (bitwise invert) with 2’s complement (invert then add 1). Also, forgetting to maintain the original bit-width when presenting results. Final Answer: 00101

Question 7

Shift register fundamentals: A shift register moves the _____ left or right. With serial loading, a word is stored by entering _____ bit per clock pulse; with parallel (broadside) loading, it takes one _____ pulse to load the word.

Accepted Answer

Introduction / Context: Shift registers are sequential logic circuits that move stored data left or right on each clock edge. They are used for serialization/deserialization, time delays, and simple state manipulation. Understanding serial versus parallel loading is key to using them effectively in digital designs. Given Data / Assumptions: A shift register stores a multi-bit word. Serial loading feeds bits one at a time on successive clocks. Parallel (broadside) loading writes all bits simultaneously on a single clock. Concept / Approach: On each active clock edge, a shift register transfers each flip-flop’s state to its neighbor, effectively moving bits left or right depending on wiring. Serial input streams in 1 bit per clock into the end cell; parallel load uses a dedicated load signal to capture an entire word at once with one clock event. Step-by-Step Solution: Identify what moves: data bits shift left or right per clock.Serial load: add one new bit each clock until the word is fully captured.Parallel load: assert load; on the next clock, all bits latch simultaneously.Thus fill the blanks: bits, one, clock. Verification / Alternative check: Datasheets for universal shift registers (e.g., 74HC194/195) describe both serial inputs (SER) and a parallel load (PL) controlled by a single clock edge, confirming the terminology. Why Other Options Are Wrong: “light” and “right” are incorrect nouns for what is shifted. “Register” is not the timebase; loading is synchronized by a clock. Common Pitfalls: Confusing direction labels (left/right) with MSB/LSB placement; mixing up the separate load enable versus the clock signal. Final Answer: bits, one, clock

Question 8

In digital electronics and computer organization, how many bits of information can a single flip-flop reliably store at any instant?

Accepted Answer

Introduction / Context: A flip-flop is the fundamental memory element in synchronous digital systems. It is used in registers, counters, state machines, and pipelines. Understanding exactly how much information a single flip-flop holds is foundational for designing wider storage structures such as n-bit registers and for reasoning about state in sequential circuits. Given Data / Assumptions: The device in question is a flip-flop (e.g., D, JK, T), clocked and bistable. We consider its stable storage capacity at a given time, not its switching behavior. Information capacity is measured in bits (binary digits). Concept / Approach: A flip-flop is a bistable circuit, meaning it has two stable states, typically labeled 0 and 1. Because information content is tied to the number of reliably distinguishable states, a bistable element stores log2(2) = 1 bit. Multiple flip-flops can be grouped to form wider words: for example, 8 flip-flops create an 8-bit register, and 32 flip-flops create a 32-bit register. But the atomic capacity of one flip-flop remains one bit regardless of type or implementation technology (TTL, CMOS, etc.). Step-by-Step Solution: Identify the device's nature: a bistable memory element with two stable states.Relate states to information: 2 distinct states → 1 bit of information.Generalize: n flip-flops → n bits; but a single flip-flop → 1 bit.Select the option that matches this capacity. Verification / Alternative check: Datapath block diagrams show that a 1-bit register cell is implemented by one flip-flop. Memory-mapped I/O often exposes control bits corresponding one-to-one with underlying flip-flops, validating the 1-bit capacity. Why Other Options Are Wrong: 2, 3, or 4 bits would require 2, 3, or 4 independent bistable elements. A single flip-flop cannot encode more than two states. “None of the above” is incorrect because 1 bit is exactly right. Common Pitfalls: Confusing a latch array or register (many flip-flops) with an individual flip-flop; assuming multilevel storage within a single standard flip-flop; overlooking that edge-triggering or preset/clear pins do not increase stored bit count—they only control the single stored bit. Final Answer: 1 bit of data

Question 9

In signed binary representation (signed-magnitude form), the leading (most significant) bit indicates the sign, and the remaining bits represent the magnitude. Fill the blanks: the leading bit stands for the _____ and the remaining bits for the ____…

Accepted Answer

Introduction / Context: Several schemes encode positive and negative integers in binary. One of the earliest and most intuitive is signed-magnitude representation. To answer correctly, you must recall what the most significant bit (MSB) denotes and how the rest of the bits encode the actual absolute value of the number. Given Data / Assumptions: The representation referred to is the signed binary numbers in signed-magnitude form. The MSB is singled out for a special role. All remaining lower-order bits form the magnitude field. Concept / Approach: In signed-magnitude, the MSB is 0 for positive and 1 for negative numbers. The remaining bits hold the magnitude as an unsigned binary value. For example, with 8 bits, +13 is 0 0001101 and −13 is 1 0001101. This differs from two’s complement, where the MSB is part of the weighted value and negative numbers are represented via bit inversion and addition of 1. Step-by-Step Solution: Identify the encoding scheme: signed-magnitude.Assign MSB role: indicates the sign (0 = positive, 1 = negative).Assign remaining bits: represent the magnitude of the integer.Choose the pair “sign, magnitude.” Verification / Alternative check: Consider 5-bit signed-magnitude: +7 = 0 00111, −7 = 1 00111. The MSB changes sign while the magnitude bits remain identical, confirming the roles. Why Other Options Are Wrong: “sign, remainder” is vague and not the standard term. “value, sign” reverses the roles. “variable, value” is unrelated to binary encoding terminology. “None of the above” is wrong because “sign, magnitude” is precisely correct. Common Pitfalls: Confusing signed-magnitude with two’s complement or one’s complement; forgetting that signed-magnitude has two zero representations (+0 and −0), which is one reason modern computers prefer two’s complement. Final Answer: sign, magnitude

Question 10

In digital logic analysis, which table lists a circuit's output for every possible combination of input logic levels (thereby defining the function completely)?

Accepted Answer

Introduction / Context: Every combinational logic function can be fully specified by enumerating all possible input combinations and their corresponding outputs. The tabular artifact that performs this enumeration is central to design, verification, and simplification (e.g., Karnaugh maps). Knowing its name and role is essential in digital systems education and practice. Given Data / Assumptions: We are describing a table-driven description of a logic function. All input combinations are listed without omission. The focus is logic states (0/1), not network routing or character codes. Concept / Approach: A truth table enumerates outputs for every input vector. For n binary inputs, there are 2^n rows. The table can represent single-output or multi-output functions and is often the starting point for algebraic minimization. “Function table” is sometimes used informally, but “truth table” is the standard term in digital design curricula and datasheets. Step-by-Step Solution: Identify the artifact: a table listing all input combinations.Associate it with digital logic function specification.Recall the widely accepted term: truth table.Select “Truth table.” Verification / Alternative check: Data sheets for logic ICs (e.g., 74xx series) include “Truth Table” sections that list inputs and resultant outputs. This confirms the conventional terminology. Why Other Options Are Wrong: Routing table relates to networks; ASCII table maps codes to characters; “Function table” is ambiguous and less canonical; “None” is wrong because the correct term exists. Common Pitfalls: Assuming a partial table suffices; omitting don’t-care conditions; confusing truth tables with state transition tables (which include present/next states for sequential machines). Final Answer: Truth table

Question 11

Convert the 16-bit signed-magnitude binary value 1000 0000 0000 1111 to its decimal equivalent (interpret the leading bit as the sign and the remaining 15 bits as magnitude).

Accepted Answer

Introduction / Context: Signed integers can be encoded in several binary formats. This problem specifies signed-magnitude, where the most significant bit (MSB) is the sign and the remaining bits are the magnitude. Correctly converting such numbers to decimal reinforces understanding of how signs and magnitudes are separated in this scheme. Given Data / Assumptions: Word size: 16 bits grouped as 1000 0000 0000 1111. Encoding: signed-magnitude (MSB is sign, others are magnitude). Magnitude field length: 15 bits. Concept / Approach: In signed-magnitude representation, MSB = 0 denotes a positive number; MSB = 1 denotes a negative number. The magnitude is read as an ordinary unsigned binary value from the remaining bits. Therefore, the task reduces to identifying sign from bit 15 and converting the lower 15 bits to decimal. Step-by-Step Solution: Inspect MSB: the pattern begins with 1 → negative number.Extract magnitude bits: 0000 0000 0000 1111.Convert magnitude: 0000 0000 0000 1111 (binary) = 8 + 4 + 2 + 1 = 15.Apply sign: negative → decimal value = −15.Choose option “−15.” Verification / Alternative check: Cross-check by comparing to the positive counterpart: 0000 0000 0000 1111 would be +15; changing the MSB to 1 simply flips the sign in signed-magnitude. No two’s-complement manipulation is needed because the encoding is not two’s complement here. Why Other Options Are Wrong: “+15” uses the right magnitude but wrong sign. “±30” has an incorrect magnitude. “None of the above” is wrong because “−15” precisely matches the signed-magnitude interpretation. Common Pitfalls: Accidentally applying two’s-complement rules (invert and add one) to a signed-magnitude number; miscounting the number of magnitude bits; overlooking that signed-magnitude has both +0 and −0 encodings, unlike two’s complement. Final Answer: -15

Question 12

Convert the binary number 101101 (base 2) to its decimal (base 10) value. Show the place-value reasoning clearly.

Accepted Answer

Introduction / Context: Binary-to-decimal conversion illustrates how positional number systems work. Each bit represents a power of two based on its position from the rightmost bit (least significant bit). Converting 101101 (base 2) to decimal by explicit expansion builds confidence for handling larger values and for reading register contents and addresses. Given Data / Assumptions: Binary string: 101101. Bit positions from right to left: 2^0, 2^1, 2^2, 2^3, 2^4, 2^5. Only positions with bit 1 contribute to the sum. Concept / Approach: Write the value as a sum of weighted bits: value = Σ(bit_i * 2^i). For 101101, the 1s occur at positions 0, 2, 3, and 5 (counting from 0 on the right). Compute each contributing power and add them to obtain the decimal result. Step-by-Step Solution: List powers of two: 2^0=1, 2^1=2, 2^2=4, 2^3=8, 2^4=16, 2^5=32.Map bits: 1 0 1 1 0 1 → positions 5, 3, 2, 0 are 1.Compute sum: 2^5 + 2^3 + 2^2 + 2^0 = 32 + 8 + 4 + 1 = 45.Decimal result: 45. Verification / Alternative check: Group into two parts: 101000 (binary) = 40 and 000101 (binary) = 5; 40 + 5 = 45, confirming the same answer with a quick mental split. Why Other Options Are Wrong: 43 misses one 2^1 contribution or miscounts a bit; 40 corresponds to 101000; 47 would require an extra 2^1 compared to our number; “None” is wrong because 45 is correct. Common Pitfalls: Reading positions from the left instead of the right; dropping a middle bit; arithmetic slips when adding powers quickly. Always enumerate the powers and mark the 1-bit positions. Final Answer: 45

Question 13

What is the highest decimal value that can be represented using 10 binary digits (10 bits)? Explain the 2^n − 1 rule.

Accepted Answer

Introduction / Context: Bit width determines numeric range. For unsigned binary numbers, the maximum representable value with n bits is 2^n − 1 because all bits set to 1 yields that sum. Understanding this rule is critical for designing counters, address buses, and buffer size limits. Given Data / Assumptions: The quantity is an unsigned value using exactly 10 bits. Each bit represents a power of two: 2^0 through 2^9. We seek the largest value with all bits set to 1. Concept / Approach: For n bits, the range is 0 to (2^n − 1). With 10 bits, that is 0 to (2^10 − 1). Since 2^10 = 1024, the highest value is 1023. This result follows from the geometric series sum: 1 + 2 + 4 + … + 2^(n−1) = 2^n − 1, which is exactly the value when all n bits are 1s. Step-by-Step Solution: Compute 2^10: 1024.Apply the formula for the maximum unsigned value: 2^n − 1 → 1024 − 1.Obtain 1023 as the highest representable value.Select option “1023.” Verification / Alternative check: Write the 10-bit all-ones pattern: 1111111111 (binary). Converting to decimal: 512 + 256 + 128 + 64 + 32 + 16 + 8 + 4 + 2 + 1 = 1023, confirming the formula-based result. Why Other Options Are Wrong: 1024 equals 2^10 and requires 11 bits to represent as an unsigned value (1 followed by ten zeros). 512 is 2^9 and is far below the maximum. “All of the above” cannot be correct because only one value is the true maximum. Common Pitfalls: Confusing the count of distinct values (2^n) with the maximum value (2^n − 1); forgetting that the smallest value is 0, not 1, for unsigned ranges. Final Answer: 1023

Question 14

In Boolean (binary) multiplication, which of the following equalities is not true? Choose the statement that violates the AND-operation rules.

Accepted Answer

Introduction / Context: In Boolean algebra, multiplication corresponds to the logical AND operation. Knowing the basic truth rules for AND is essential for analyzing logic circuits, simplifying expressions, and validating gate-level designs. This question asks you to spot the statement that contradicts the AND truth table. Given Data / Assumptions: Boolean variables take values 0 (false) or 1 (true). Multiplication (·) represents AND. We compare simple two-operand cases. Concept / Approach: The AND truth table is: 0·0=0, 0·1=0, 1·0=0, 1·1=1. The operation outputs 1 only when both inputs are 1. Therefore, any statement asserting 0·1=1 or 1·0=1 is false. All other canonical combinations follow the rules above. Step-by-Step Solution: List the four possible operand pairs for AND: (0,0), (0,1), (1,0), (1,1).Apply AND rule: output is 1 iff both inputs are 1.Evaluate each given equality and compare with the rule.Identify the violation: “0 x 1 = 1.” Verification / Alternative check: Gate-level view: an AND gate requires both inputs high to drive its output high; with one input at 0, the output is forced low. This physical intuition matches the algebraic rule. Why Other Options Are Wrong: 0·0=0, 1·0=0, and 1·1=1 are all correct AND identities. “None of the above” is wrong because there is a clearly incorrect statement present. Common Pitfalls: Confusing Boolean multiplication (AND) with arithmetic multiplication; in arithmetic, 0×1=0 too, but the conceptual grounding here is logical truth, not numeric magnitude. Final Answer: 0 x 1 = 1

Question 15

Convert the binary number 1100011 (base 2) to octal (base 8). Show the 3-bit grouping from the right and the resulting octal digits.

Accepted Answer

Introduction / Context: Binary-to-octal conversion is efficient because each octal digit corresponds exactly to three binary bits. Grouping the binary number into 3-bit chunks from the right yields the octal digits directly. This method is widely used for compactly representing long binary strings. Given Data / Assumptions: Binary value: 1100011 (base 2). We convert without changing the numeric value, only the base representation. Leading zeros may be added on the left to complete a 3-bit group. Concept / Approach: Starting at the least significant end, partition the binary string into 3-bit groups and map each group to its octal digit: 000→0, 001→1, …, 111→7. If the leftmost group has fewer than 3 bits, pad with leading zeros to the left. Concatenate the mapped octal digits in order to form the final octal number. Step-by-Step Solution: Write the binary: 1 100 011 (grouped from right).Pad the leftmost group to 3 bits: 001 100 011.Map groups: 001→1, 100→4, 011→3.Concatenate octal digits: 1 4 3 → 143 (base 8). Verification / Alternative check: Decimal cross-check: 1100011 (base 2) = 64 + 32 + 2 + 1 = 99. Now 143 (base 8) = 164 + 48 + 3 = 64 + 32 + 3 = 99. The results match, confirming correctness. Why Other Options Are Wrong: 140 (base 8) equals 96 decimal; 147 (base 8) equals 103 decimal; 149 is not a valid octal number because 9 is not an octal digit; “None” is incorrect because 143 is correct. Common Pitfalls: Forgetting to pad the leftmost group; grouping from the left instead of the right; accidentally converting to hexadecimal mapping (4-bit groups) instead of octal (3-bit groups). Final Answer: 143

Question 16

Shift registers are versatile sequential circuits. Which applications can a shift register perform in digital systems?

Accepted Answer

Introduction / Context: Shift registers are chains of flip-flops that move data one stage per clock under control of shift and load signals. Their ability to shift and temporarily hold data makes them essential for interfacing, timing alignment, and simple data processing tasks. Recognizing their common applications helps in selecting the right structure for a given design need. Given Data / Assumptions: We consider generic n-bit shift registers with parallel load and/or serial input/output options. Clocked synchronous operation is assumed. Applications are within typical digital system designs. Concept / Approach: Parallel-to-serial: load n bits in parallel and shift them out one bit per clock for transmission over a single line (e.g., SPI MOSI). Serial-to-parallel: receive serial bits over multiple clocks and present them simultaneously as an n-bit word (e.g., SPI shift-in). Digital delay line: each clock moves data one stage, so after k stages the output reproduces the input delayed by k clock periods—useful for timing alignment and pulse stretching. Step-by-Step Solution: Identify shift register topology (e.g., SISO, SIPO, PISO, PIPO).Map each topology to the listed functions (conversion or delay).Confirm that standard devices support all three applications.Choose the comprehensive option “All of the above.” Verification / Alternative check: Datasheets for classic 74HC/74LS shift registers (e.g., 74HC595, 74HC165) explicitly show parallel/serial conversion capabilities and timing diagrams demonstrating clocked delay behavior, validating the coverage of use cases. Why Other Options Are Wrong: Each single-purpose answer is incomplete. Shift registers are not limited to only one of the listed functions; they commonly perform all three depending on configuration. Common Pitfalls: Assuming a shift register must be bidirectional to do both conversions (many designs use separate SIPO and PISO parts); ignoring setup/hold and clock skew, which affect reliable shifting. Final Answer: All of the above

Question 17

Identify the first widely used integrated logic family in early monolithic IC history (preceding DTL and TTL).

Accepted Answer

Introduction / Context: The evolution of digital logic families traces the development of integrated circuits from simple, low-density gates to today's high-performance CMOS. Recognizing which family appeared first helps contextualize trade-offs in speed, power, and integration levels across generations of technology. Given Data / Assumptions: We refer to early monolithic integrated logic used in the 1960s era. Options include RTL (resistor–transistor logic), DTL (diode–transistor logic), TTL (transistor–transistor logic), and MOS (metal–oxide–semiconductor). The question asks for the earliest among the commonly cited integrated families. Concept / Approach: Resistor–transistor logic (RTL) emerged first in monolithic IC form and offered simple inverter and gate structures using resistors for input networks and a single transistor for switching. DTL followed with improved noise margins using diodes in the input networks. TTL later became dominant in the late 1960s and 1970s because of better speed and fanout. MOS logic matured subsequently and ultimately led to CMOS dominance due to extremely low static power and high integration density. Step-by-Step Solution: Order the families historically: RTL → DTL → TTL → MOS/CMOS (widespread later).Select the earliest widely used integrated family: RTL.Confirm that the others either came later or became dominant later.Choose “RTL.” Verification / Alternative check: Historical accounts of early ICs from Fairchild and other pioneers describe RTL as the first integrated logic family in production, with DTL and TTL improving on speed and noise margin thereafter. Why Other Options Are Wrong: DTL and TTL post-date RTL in integrated form; MOS became significant later with PMOS/NMOS and then CMOS processes. “None of the above” is incorrect because RTL is the correct earliest family. Common Pitfalls: Confusing discrete-circuit inventions with integrated versions; assuming TTL came first due to its later popularity; overlooking that CMOS dominance is modern and not the earliest in IC history. Final Answer: RTL

Question 18

In classic digital electronics, the 7400-series (standard TTL) catalog includes a wide range of small-scale integration (SSI) and medium-scale integration (MSI) logic chips used to build complete digital circuits and systems. Which integration level…

Accepted Answer

Introduction / Context: The 7400-series, often called “standard TTL” (Transistor–Transistor Logic), is a foundational family of logic integrated circuits widely used in education and industry. Understanding how these parts are categorized by integration scale helps learners select appropriate devices for counters, decoders, multiplexers, and basic glue logic. Given Data / Assumptions: The statement references “SSI and ____ chips.” Context is standard TTL 74xx families (e.g., 7400 NAND, 74138 decoder, 7474 flip-flops). We are matching the correct integration level term. Concept / Approach: Integration scale classifies how many logic gates or functions a chip contains. SSI (small-scale integration) typically has a few gates or flip-flops per package. MSI (medium-scale integration) includes more complex functions such as multiplexers, decoders, adders, or register files. LSI and VLSI exceed these in complexity but are not the canonical pair used to describe the 7400 series’ breadth. Step-by-Step Solution: Identify the well-known pairing: “SSI and MSI.”Confirm examples: SSI → 7400 (quad 2-input NAND). MSI → 74181 (ALU nibble), 74138 (3-to-8 decoder).Conclude that the correct completion is MSI. Verification / Alternative check: Standard texts and catalogs list many 74xx devices that fall squarely into SSI and MSI categories; LSI/VLSI are typically separate CMOS or custom families, not the focus of classic TTL catalogs. Why Other Options Are Wrong: LSI: higher integration than typically associated with the classic TTL range described in the statement.MOS/MOSFET: refer to device technology, not integration scale in this context.None of the above: incorrect because MSI is the standard completion. Common Pitfalls: Confusing technology (TTL vs. CMOS) with integration scale; assuming LSI/VLSI were equally common in early 74xx learning contexts. Final Answer: MSI

Question 19

In digital systems, a demultiplexer (DEMUX) takes one input and routes it to one of many outputs based on select lines. What is another common name for a demultiplexer?

Accepted Answer

Introduction / Context: Multiplexers (MUXes) and demultiplexers (DEMUXes) are complementary switching elements used throughout digital design, communications, and data acquisition. Understanding their alternate names clarifies datasheets and schematic notations. Given Data / Assumptions: A demultiplexer has one data input, multiple outputs, and select lines. The function is to distribute the single input to one of the outputs. We look for a standard synonym used in textbooks and vendor literature. Concept / Approach: By definition, a demultiplexer performs the inverse role of a multiplexer. Where a MUX is a “data selector,” a DEMUX is a “data distributor.” The select lines choose which single output line receives the input value. Step-by-Step Solution: Recall: MUX = many inputs → one output (data selector).DEMUX = one input → many outputs (data distributor).Match the synonym: “data distributor.” Verification / Alternative check: Check block symbols: a DEMUX symbol shows one input feeding a bank of outputs labeled by select lines, consistent with distribution. Why Other Options Are Wrong: data selector: synonym for multiplexer, not demultiplexer.multiplexer: opposite device.encoder: converts active input line to a coded output, a different function.None of the above: incorrect because “data distributor” is correct. Common Pitfalls: Confusing MUX and DEMUX names; forgetting that select line naming conventions may differ (S0..Sn vs. A..C). Final Answer: data distributor

Question 20

In linear integrated circuits, why are field-effect transistors (FETs) commonly included in input stages?

Accepted Answer

Introduction / Context: Operational amplifiers and other linear ICs often use FETs at the input because FET gate channels behave like extremely high-impedance nodes. This design choice improves signal integrity when interfacing with high-impedance sensors or small signals. Given Data / Assumptions: We discuss linear IC input stages. FET characteristics: very high input impedance; ability to implement large on-chip resistances. We are not optimizing for switching speed but for analog performance. Concept / Approach: FET gates draw negligible DC current, which raises the input resistance into megaohm or gigaohm ranges. In IC processes, FET geometries can also realize large value “pseudo-resistors” where discrete resistors would be bulky or impractical. Step-by-Step Solution: Identify analog need: avoid loading sources → require high Rin.Use FET gates to realize high input resistance.Leverage device geometry to synthesize large resistive elements on die.Therefore both (a) and (b) are correct. Verification / Alternative check: Compare BJT vs. JFET/MOSFET input op-amps: FET inputs excel where source impedance is high or bias currents must be minimal. Why Other Options Are Wrong: increase device complexity: not the primary design goal; complexity may increase but is not the reason.Single choices (a) or (b) alone understate typical benefits.None: incorrect because FETs do provide both advantages. Common Pitfalls: Assuming FET inputs are always superior; BJTs may offer lower noise or higher transconductance in some applications. Final Answer: (a) and (b) above

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