I have three computer science assignment. I need A+ grades so please only bid if you can do good.

MULUNGUSHI UNIVERSITY

Pursing the frontiers of knowledge

CENTRE FOR ICT EDUCATION

ICT 241 Digital Design

Assignment Type: Lab 1

Fundamental Digital Circuits: Storage Units/ Registers

IInnttrroodduuccttiioonn

Logic alone does not a system make. Boolean equations provide the means

to transform a set of inputs into deterministic results. However, these equations

have no ability to store the results of previous calculations upon which new

calculations can be made. Digital systems operate by maintaining state to

advance through sequential steps in an algorithm. State is the system’s ability to

keep a record of its progress in a particular sequence of operations. A system’s

state can be as simple as a counter or an accumulated sum. State-full logic

elements called flip-flops are able to indefinitely hold a specific state (0 or 1) until

a new state is explicitly loaded into them.

CClloocckkiinngg

Before we discuss sequential logic, we must first introduce a way to order

events. The fact that a sequential circuit uses past inputs to determine present

outputs indicates we must have event ordering. Some sequential circuits are

asynchronous, which means they become active the moment any input value

changes. Synchronous sequential circuits use clocks to order events. A clock is a

circuit that emits a series of pulses with a precise pulse width and a precise

interval between consecutive pulses. This interval is called the clock cycle time.

Clock speed is generally measured in megahertz (MHz), or millions of pulses per

second. Common cycle times are from one to several hundred MHz. Flip-flops

load a new state when triggered by the transition of an input clock. A clock is also

considered as a repetitive binary signal with a defined period that is composed of

0 and 1 phases. In addition to a defined period, a clock also has a certain duty

cycle, the ratio of the duration of its 0 and 1 phases to the overall period. An ideal

clock has a 50/50 duty cycle, indicating that its period is divided evenly between

the two states. Clocks regulate the operation of a digital system by allowing time

for new results to be calculated by logic gates and then capturing the results in

flip-flops. A clock is used by a sequential circuit to decide when to update the

state of the circuit (when do "present" inputs become "past" inputs?). This means

that inputs to the circuit can only affect the storage element at given, discrete

instances of time. Most sequential circuits are edge-triggered (as opposed to

being level-triggered). This means they are allowed to change their states on

either the rising or falling edge of the clock signal, as seen below in fig. 1.

Fig.1. A Clock Signal Indicating Discrete Instances of Time

FFlliipp--ffllooppss

There are several types of flip-flops, but the most common type in use today the

most common in use being the D flip-flop. Other types of flip-flops include RS, T

and JK flip-flops. The storage elements considered in this lab concentrate on the

use of D and JK flip-flops as well as basic logic. Rising-edge flops are the norm,

although some flops are falling-edge triggered. A falling-edge triggered flop is

indicated by placing an inversion bubble at the clock input. Operation is the same,

with the exception that the polarity of the clock is inverted.

TASK 1: Shift Register

i. Using Logisim, draw the full digital circuit of a 4-bit shift register as shown

below in fig. 2.

Fig. 2. 4-bit serial-in, parallel-out (SIPO) shift register

ii. Take a screenshot of the circuit you will create with a couple of different

trigger states, i.e. the register at the fourth pulse with data bits of sequence 1101.

Note that Data0 is the main input while Clock0 is the clock pulse.

iii. Play around with different storage values of flip-flop as you change the

clocking and take note of the changes and eventually how the register works.

iv. How does the SIPO differ from PISO and which of the two finds more use

in digital systems today?

iv. Conclude this task by giving the advantages and disadvantages of the

above circuit and also list practical application of the SIPO shift register.

TASK 2: 4-Bit Register

i. Using Logisim, draw the full circuit of a 4-bit register as shown in the

diagram below.

Fig. 3. A 4-Bit Register

ii. Take a screenshot of the circuit you will create with a couple of different

trigger states.

iii. Play around with different storage values of flip-flop as you change the

clocking and take note of the changes and eventually how the register works.

iv. Conclude this task by giving areas of practical application of this circuit.

TASK 3: 4-Bit Synchronous Counter Using JK Flip-Flops

i. Using Logisim, draw the full digital circuit of a 4-Bit Synchronous Counter

using JK Flip-Flops as shown in the figure below.

Fig.4. A 4-Bit Synchronous Counter Using JK Flip-Flops

ii. Take a screenshot of the circuit you will create with a couple of different

trigger states.

iii. Play around with different storage values of flip-flop as you change the

clocking and take note of the changes and eventually tell how the register works.

iv. Conclude this task by giving areas of practical application of this circuit.

v. Give an overall conclusion about this lab and the entire tasks herein.

Your lab report should include screenshots taken on every necessary stage and

every screenshot taken should be followed by an explanation. Number the steps

your work properly and name your screenshots diagrams accordingly. Your last

page should constitute the overall conclusion pertaining to the work done.