Digital Logic · Unit 7 · 6 hrs
Registers and Counters
Exam-focused notes for Registers and Counters (Digital Logic, CSC116): what the TU syllabus asks and how it has actually been tested, with 16 solved past questions from this unit.
What this unit covers
- Registers
- Shift registers
- Ripple Counters
- Synchronous Counters
- Timing Sequences
- The memory
Synchronous Counters
Differentiate between synchronous and asynchronous counter. Design a 3-bit synchronous binary counter using T Flip Flop. Draw its timing diagram.[10]
--- Feature Synchronous Counter Asynchronous Counter (Ripple Counter) --------- Clock All flip-flops are triggered by the same common clock pulse simultaneously Each flip-flop is triggered by the output of the previous flip-flop Speed Faster - no propagatio...
Full solved answer →What is asynchronous counter? Design synchronous counter that counts the sequences of 0-1-4-6-7 using T flip-flop.[10]
- Counter type to design: synchronous counter - Count sequence: 0 → 1 → 4 → 6 → 7 → (back to 0) - Flip-flop type: T flip-flop - Highest state = 7 → needs 3 flip-flops ($Q2 Q1 Q0$) - Used states: 0, 1, 4, 6, 7 - Unused states (don't care): 2, 3, 5 --- An asy...
Full solved answer →Differentiate between combinational circuit and sequential circuit. Design mod-10 synchronous counter using J-K flip-flop. Show necessary truth tables and K-maps.[10]
- Counter type: Mod-10 (decade / BCD) synchronous counter - Flip-flop type: J-K flip-flop - Count sequence: $0 \to 9$ then back to $0$ - Number of flip-flops: $2^4 = 16 \ge 10 \Rightarrow 4$ flip-flops - States $1010$ to $1111$ (10-15) are unused → don't-ca...
Full solved answer →Differentiate between synchronous and asynchronous counter. Design mod-7 synchronous counter using T-flip flop. Show necessary truth tables and k-maps.[10]
- Counter type required: Mod-7 synchronous counter - Flip-flop type: T flip-flop - Count sequence: 0 to 6 (7 states), then back to 0 - Deliverables: comparison table, truth tables, K-maps, design No numeric data missing. All information is complete. --- Fea...
Full solved answer →Shift registers
Mention different types of shift registers. Explain SIPO with timing diagram. [5]
As stated in the notes, a shift register is any register capable of shifting its binary information either to the right or to the left. It consists of a chain of flip-flops connected in cascade, with the output of one flip-flop connected to the input of the...
Full solved answer →What is shift register? Explain 4-bit SISO and PIPO with timing Diagram. [5]
Any register capable of shifting its binary information either to the right or to the left is called a shift register. It consists of a chain of flip-flops connected in cascade, where the output of one flip-flop is connected to the input of the next flip-fl...
Full solved answer →Provide one example where shift left operator can be used. Explain serial-in-serial-out register. [5]
--- The shift left operation is commonly used for fast multiplication by powers of 2. Example: Let the binary number stored in a register be: After applying one shift left operation: After applying two shift lefts: Observation: Operation Binary Decimal Effe...
Full solved answer →Provide one example where shift right operation can be used. Explain parallel-in parallel-out register. [5]
--- A very common and practical use of the shift right operation is in fast division by powers of 2. Example: Consider an 8-bit register holding the binary number: Performing a 1-bit shift right operation: Result: The value is divided by 2 (24 / 2 = 12), wi...
Full solved answer →What is the difference between a serial and parallel transfer? Explain how to convert serial data to parallel and parallel data to serial. What type of register is needed? [5]
--- Feature Serial Transfer Parallel Transfer --------- Data movement One bit per clock pulse, in sequence All bits transferred simultaneously in a single clock pulse Speed Slower (n clock pulses for n bits) Faster (only 1 clock pulse needed) Wires/Lines re...
Full solved answer →What is the difference between a serial and parallel transfer? Explain how to convert serial data to parallel and parallel data to serial. What type of register is needed? [5]
Feature Serial Transfer Parallel Transfer --------- Data movement One bit per clock pulse, in sequence All bits transferred simultaneously in a single clock pulse Speed Slower (n clock pulses for n bits) Faster (only 1 clock pulse needed) Wires/Lines requir...
Full solved answer →Ripple Counters
Design a 2 bit asynchronous binary counter using T Flip Flop. Draw its timing diagram. [5]
A binary ripple (asynchronous) counter consists of a series connection of complementing flip-flops where the output of each flip-flop is connected to the clock input of the next higher-order flip-flop. The flip-flop holding the Least Significant Bit (LSB) r...
Full solved answer →Design an asynchronous Mod 11 up counter using T flip flop. [5]
- Counter type: Asynchronous (ripple) - Modulus: 11 (counts 0 to 10, i.e. 11 distinct states) - Flip-flop type: T flip-flop - Direction: Up counter No numeric values are missing. The design is fully specified. --- We need enough flip-flops to represent 11 s...
Full solved answer →What are the practical implications of down counter? Explain BCD ripple counter. [5]
--- A down counter is a counter that counts in decreasing order (e.g., from 15 to 0 for a 4-bit counter). Its practical implications include: 1. Timer/Countdown Applications: Used in digital timers, microwave ovens, and bomb-timer circuits where counting do...
Full solved answer →What are the practical implications of up counter? Explain Binary ripple counter. [5]
--- An up counter is a counter that counts in increasing order (0, 1, 2, 3, ..., 2ⁿ - 1) and then resets back to 0. Its practical implications include: 1. Frequency Division: An up counter divides the input clock frequency. Each flip-flop divides the freque...
Full solved answer →Illustrate the use of Binary ripple counter and BCD ripple counter. [5]
--- A binary ripple counter consists of a series connection of complementing flip-flops (T flip-flops or JK flip-flops) where the output of each flip-flop is connected to the clock input of the next higher-order flip-flop. The flip-flop holding the Least Si...
Full solved answer →Design a 4-bit binary ripple counter with D flip-flops. [5]
A binary ripple counter is a series connection of complementing flip-flops where the output of each flip-flop is connected to the clock input of the next higher-order flip-flop. The LSB flip-flop receives the incoming count pulses. Since we need to use D fl...
Full solved answer →Make Unit 7 stick
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