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Question 1
Marnel Field Centre uses electronic observation stations to collect wildlife records. Its technicians maintain the stations’ stored data and logic circuits.
The stations store observations using binary encoding.
I.
State one type of data that can be stored using binary encoding.
[1]
II.
State two properties of an uncompressed bitmap image file that affect its storage size.
[2]
State one Boolean operator that could be implemented by a logic gate in a station.
[1]
A technician proposes a different Boolean expression for a station’s alert circuit. Explain how truth tables can establish whether the proposed expression preserves the original circuit’s behaviour.
[2]
Distinguish between binary and hexadecimal representations of the positive integer identifiers used by the stations. Give three differences.
[3]
Explain one benefit of simplifying a station’s logic diagram so that it uses fewer gates while preserving its outputs.
[2]
Question 2
Virel Stageworks uses an electronic controller to operate stage equipment. The controller processes binary signals and stores equipment identifiers and performers’ names.
I.
State one logic gate that takes two binary inputs and produces one binary output.
[1]
II.
State two symbols that are valid hexadecimal digits but are not valid binary digits.
[2]
An equipment identifier is hexadecimal 6B. State its equivalent eight-bit binary representation.
[1]
Input A is 1 when a movement command is active. Input B is 1 when an obstruction is detected. The motor-enable output is Y = A AND NOT B. Construct the truth table for the two inputs A and B, including a column for NOT B. List input combinations in binary order.
[2]
The controller must store performers’ names from many writing systems. Distinguish between ASCII and Unicode for representing these names. Give three differences.
[3]
A warning output is defined by W = (P OR Q) AND (P OR NOT Q), where P and Q are binary fault signals. Explain why changing Q cannot change W when P remains fixed.
[2]
Question 3
Ostel Harbour Survey operates recording buoys that store images and audio. Each buoy uses a logic controller to decide when to record and identifies its recordings using hexadecimal values.
I.
State one hexadecimal digit that represents a decimal value greater than 9.
[1]
II.
State two functions that networks of logic gates can perform in a buoy’s computer.
[2]
A recording has the binary identifier 11010110. State its hexadecimal equivalent.
[1]
The controller’s recording output is R = (A OR B) AND C. A is a manual request, B is a scheduled request and C indicates that recording is enabled. Construct a logic diagram for this expression using standard gate symbols. Label the inputs and output.
[2]
Compare and contrast how the buoy’s bitmap images and sampled audio are represented using binary. Give three points.
[3]
The survey team wants its recordings to represent more detail. Explain one change to either image or audio encoding that would achieve this while increasing uncompressed storage requirements. Assume recording duration and the number of images remain unchanged.
[2]
Question 4
Veyra Ceramics uses a digital system to monitor its kilns. The system stores photographs, spoken inspection notes and equipment identifiers, and uses logic circuits to generate status signals.
Outline how a bitmap photograph of a finished ceramic item is represented in binary.
[2]
An equipment identifier is stored as hexadecimal 6B. State its equivalent eight-bit binary representation.
[1]
Two status inputs, A and B, each have the value 1 when the corresponding kiln is operating. An output, D, is 1 only when exactly one kiln is operating. Construct the truth table for D using the two inputs A and B. List the input combinations in binary order.
[2]
Outline how a spoken inspection note is represented in binary.
[2]
Outline why the system needs information about the encoding or format when retrieving stored binary data.
[2]
A separate circuit in the monitoring system has three binary inputs, P, Q and R. Its output is given by:
Y = (P AND Q AND R) OR (P AND Q AND NOT R) OR (P AND NOT Q AND R)
Deduce a simplified sum-of-products expression for Y, showing your working. Construct an equivalent circuit using only two-input NAND gates. Express your circuit as a list of gates and their connections.
[4]
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