Logic Systems N3 — Document
April 2020 — N3 — Logic Systems
N3
2020
Nated Engineering
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Q1— Section header —
1.1EF,F + 37,3 + 11101101,1011 Convert the final answer to the octal system. (5\
1.2
1.34,5 Use the one's complement method and convert the final answer to the octal system. (5\
1.420
Q2— Section header —
2.1Sketch the block diagram and complete the truth table for a full adder that use two half adders and an OR gate. (6\
2.2Encode the following into the ASCII code: (F6$\ (5\
2.3The state of a 12 bit coder is 100101010111. What is the content if it represents
2.3.1Gray code
2.3.2
2.4Differentiate between the terms word and word length as used in ogic systems
2.5Define the term alpha numeri c code and give ONE example of an alphanumeric code. (2\
Q3— Section header —
3.1Indicate whether the following statements are TRUE or FALSE by writing only 'True' or 'False' next to the questio n number (3.1.1
3.1.5\ in the ANSWER BOOK.
3.1.1Power is connected to pins 7 and 14 of a 7408 quad two input AND gate IC to allow voltage for all four AND gates on the IC.
3.1.2A NOR gate output is low if any of its inputs is low
3.1.3n OR array is programmed by blowing fuses to eliminate selected variables from the output functions.
3.1.4The output of an A ND gate with three inputs, A, B and C, is high when A = 1, B = 1, C = 1.
3.1.5
3.2The following IEC symbol is used in digital circuits to represent a gate:
3.2.1Which gate does the IEC symbol represent (1\
3.2.2Draw and full y label the switch circuit for the gate named in
Q3— Section header —
3.2.3Construct a truth table for the gate named
Q3— Section header —
3.3Given below is a circuit diagram that consists of an AND gate, a NAND gate, two NOR gates and an XOR gate. Copy and complete the following truth table for the circuit: (5\
3.4Make a neat labelled sketch of the circuit diagram f the following Boolean expression without changing or simplifying the expression: Z=ABCABAC [20]20
Q4— Section header —
4.1Various options are given as possible answers to the following questions. Choose the answer and write only the letter (A D\ next to the question number (4.1.1
4.1.5\ in the ANSWER BOOK.
4.1.1Which ONE of the following statements best describes volatile memory? Memory that retains stored information when ele ctrical power is removed
4.1.2How can UV erasable PROMs be recognised? The part number always starts with a U as in U12. There is a small window on the chip. It has
4.1.3An 8 bit address code can select locations in memory 8 locations in memory 65,536 locations in memory 131,072 locations in memory
4.1.4
4.1.5
4.2The figure below shows the logic circuit diagram of type master slave flip flop.
4.2.1Draw the truth table for the D type master slave flip flop (2\
4.2.2Why is the D type master slave flip flop known as a delay flip flop? (2\
4.2.3What is the function of the NOT gate betwee n the master and slave on the D type master slave flip flop? (2\
4.3Write the abbreviation USB in full. (2\
4.4Name THREE types of secondary memories (3\
4.5Give FOUR advantage of semiconductor memory. (4\ [20]20
Q5— Section header —
5.1Various options are given as possible answers to the followin g questions. hoose the answer and write only the letter (A D\ next to the question number (5.1.1
5.1.5\ in the ANSWER BOOK.
5.1.1The MOD 10 counter is als o referred to as a counter. ripple BCD decade circuit
5.1.2A sequential circuit design is used to decode an end count. count in a random order count down count up
5.1.3Which segments (by letter\ of a seven egment display must active to display a digit 6? b, c, d, e, f and g a, b, c, d and f a, c, d, e, f
5.1.4The minimum number of flip flops that can be used to construct a modulus 5 counter:
5.1.5
5.2Indicate whether the f ollowing statements are TRUE or FALSE by writing only 'True' or 'False' next to the question number (5.2.1
5.2.5\ in the ANSWER BOOK.
5.2.1A ripple counter is an asynchronous counter.
5.2.2The MOD number of a Johnson coun ter will always be equ al to half the number of flip flops in the counter.
5.2.3Bidirectional shift registers can shift data either right or left.
5.2.4In a synchronous counter each state is clocked by the same pulse.
5.2.5
5.3Name TWO types of circulating registers. (2\
5.4Study the diagram below and answer the questions.
5.4.1Which binary number or numbers ll switch on the LED in the counter (4\
5.4.2How many flip flops are used to construct the diagram (2\
5.4.3What will the output of the diagram be after clock pulses if it is not set before the counting commence (2\ [20] OTAL:20
Mark Allocation
Total100 marks
Sections20 + 20 + 20 + 20 + 20 = 100 marks
Key Information
Contact Number0010101011
Paper information
TitleDocument
SubjectLogic Systems
LevelN3
Document typeQuestion paper
Year2020
MonthApril
Pages9
Downloads3
Examination context
Decade2020s
Years ago6y
SeasonAutumn (SH)
Start dayWednesday
Exam periodApril 2020
Days since exam2,385
About Logic Systems examination preparation
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