TEJ3M · Exam review

Computer Engineering Exam Review

A practice exam with questions from all 7 units, then the key facts from every lesson, unit by unit. For a deeper look at one unit, open its test review.

Unit test reviews

Practice exam

35 questions, the same number from each unit. Each one shows the lesson it comes from.

Unit 1: The Computer System Model
1
Which component belongs to the PROCESS stage rather than to input, output or storage?
Unit 1: Binary, Decimal and Hexadecimal
2
Convert $1001011 0_{2}$ to decimal.
Unit 1: Representing Data: Bits, Bytes and Files
3
An image is 800 × 600 pixels at 16-bit colour. What is its size in bytes?
bytes
Unit 1: Representing Data: Bits, Bytes and Files
4
How many bits are in 3 KiB? (1 KiB = 1024 bytes)
bits
Unit 1: Generations, Moore's Law and Where Hardware Is Going
5
Match each trend to its description.
Cloud computing
Edge computing
Internet of Things
Quantum computing
Unit 2: The CPU and the Motherboard
6
Which register holds the address of the next instruction to be fetched?
Unit 2: Memory and Storage
7
Order these from fastest access time to slowest.
1. 1L2 cache
2. 2Hard disk drive
3. 3Main memory (DRAM)
4. 4CPU register
Unit 2: Building a System and Connecting Peripherals
8
Which of these can safely be connected while the computer is running?
Unit 2: Firmware, POST and the Boot Sequence
9
A technician changes SATA mode from AHCI to RAID in firmware on a working Windows machine. What happens next?
Unit 2: Operating Systems, File Systems and Maintenance
10
A file system uses 4 KB blocks. How many blocks does a 10 000 byte file occupy? (Blocks cannot be shared between files.)
blocks
Unit 3: Network Types, Topologies and Media
11
Which best describes the difference between a LAN and a WAN?
Unit 3: The OSI and TCP/IP Models
12
Order the OSI layers from layer 1 to layer 4.
1. 1Data link
2. 2Transport
3. 3Network
4. 4Physical
Unit 3: IP Addressing and Subnetting
13
How many usable host addresses does a /27 subnet provide?
Unit 3: IP Addressing and Subnetting
14
Two hosts are 10.1.1.5/24 and 10.1.2.5/24 with no router between them. Can they communicate?
Unit 3: Network Devices, Cabling and Security
15
Why must you avoid untwisting more than about 13 mm of each pair when terminating UTP?
Unit 4: Voltage, Current, Resistance and Power
16
A 330 Ω resistor has 5 V across it. What current flows, in milliamps?
mA
Unit 4: Components and Schematic Diagrams
17
Why must an LED never be connected directly across a supply?
Unit 4: Series, Parallel and Voltage Dividers
18
In a series circuit with a 100 Ω and a 900 Ω resistor across 10 V, how is the voltage shared?
Unit 4: Logic Gates and Truth Tables
19
Why must an unused input on a CMOS logic chip be tied high or low?
Unit 4: Boolean Algebra and Simplification
20
Order these simplification steps for $A \cdot B + A \cdot B^{'}$ .
1. 1Apply the complement law to $B + B^{'}$
2. 2Verify the result with a truth table
3. 3Apply the identity law to $A \cdot 1$
4. 4Factor out the common variable A
Unit 5: Variables, Data Types and Input/Output
21
What does input() return when the user types 42?
Unit 5: Selection: if, elif and else
22
This chain is written as if m >= 50: Pass, elif m >= 80: Excellent. What does a mark of 85 print?
Unit 5: Loops: while and for
23
Where must an accumulator be initialized?
Unit 5: Lists and Strings
24
Which loop correctly adds 5 to every mark in a list, modifying the list itself?
Unit 5: Functions, Errors and Debugging
25
Why is it better for a function to return a value than to print it?
Unit 6: Microcontrollers and the Arduino
26
Which function runs only once when an Arduino is powered on?
Unit 6: Digital Input and Output
27
A button is wired between a pin and 5 V with no other components. What does the pin read when the button is NOT pressed?
Unit 6: Analog Inputs and Sensors
28
analogRead() returns 512. What voltage is on the pin? Answer in volts to 2 decimal places.
V
Unit 6: Analog Inputs and Sensors
29
What is the smallest voltage change an Uno's 10-bit ADC can detect across a 5 V range? Answer in millivolts, to 1 decimal place.
mV
Unit 6: PWM, Motors and Control Systems
30
Match each component to its role in a motor circuit.
Transistor
Flyback diode
H-bridge
Common ground
Unit 7: Environmental Impact and E-Waste
31
For a typical laptop, which stage of its lifecycle consumes the most energy?
Unit 7: Environmental Impact and E-Waste
32
What must be done to a hard drive before donating a computer?
Unit 7: Societal Impact, Ethics and Security
33
Which measure most reduces the risk of a successful attack on a typical organization?
Unit 7: Workplace Safety, Standards and Careers
34
What does WHMIS stand for?
Unit 7: Workplace Safety, Standards and Careers
35
What is the correct handling of a soldering iron between joints?

Key facts by unit

Unit 1: Introduction to Computers

The Computer System Model

Every computing system is Input → Process → Output, with Storage attached to the process stage.
RAM is volatile (loses data without power); storage is non-volatile (keeps it).
Hardware is physical; software is instructions; firmware is software stored permanently in hardware.
System software manages the machine; application software does a user's task.
Von Neumann architecture: one memory holds both instructions and data — the stored-program concept.

Binary, Decimal and Hexadecimal

Binary place values from the right: $1, 2, 4, 8, 16, 32, 64, 128$ — doubling each time.
An $n$ -bit number can represent $2^{n}$ different values, from $0$ to $2^{n} - 1$ .
One byte = 8 bits = values 0 to 255 = exactly two hex digits.
Four bits = one hex digit, always. $16 = 2^{4}$ is the reason hex exists.
Decimal → binary: divide by 2 repeatedly and read the remainders BOTTOM to TOP.
Hex digits above 9: A=10, B=11, C=12, D=13, E=14, F=15.

Representing Data: Bits, Bytes and Files

8 bits = 1 byte. Lowercase b means bits, uppercase B means bytes.
1 KiB = 1024 B, but 1 kB = 1000 B. Drive makers use the second; operating systems often label the first as "GB".
ASCII: 'A' = 65, 'a' = 97, '0' = 48. The gap between upper and lower case is always 32.
Image size in bits = width × height × colour depth; divide by 8 for bytes.
$n$ -bit colour depth gives $2^{n}$ colours; 24-bit gives 8 bits per RGB channel = 16.7 million.
Lossless compression is reversible; lossy compression permanently discards data.

Generations, Moore's Law and Where Hardware Is Going

The four generations are defined by their switching device: vacuum tube → transistor → integrated circuit → microprocessor.
Moore's law: transistors on an economical chip double roughly every two years. It is an economic observation, not a physical law.
Clock speeds plateaued near 3–4 GHz around 2005 because power and heat rise steeply with frequency.
The industry responded with more cores, not faster ones — which only helps software written to run in parallel.
The memory wall: CPU speed outpaced RAM speed, so cache exists to hide the gap.

Unit 2: Hardware, Software and Operating Systems

The CPU and the Motherboard

The machine cycle is fetch → decode → execute → store, repeated billions of times per second.
Inside a core: control unit (directs), ALU (calculates), registers (hold the current values).
The program counter holds the address of the NEXT instruction.
Three buses: address (where), data (what), control (read or write, and when).
A 32-bit address bus can address $2^{32}$ bytes = 4 GiB — the historical 32-bit RAM ceiling.
Clock speed only compares fairly within one CPU generation; cores, cache and IPC matter as much.

Memory and Storage

The hierarchy runs registers → L1 → L2 → L3 → RAM → SSD → HDD, getting slower and larger each step.
Everything above the SSD line is volatile.
RAM is read-write and volatile; ROM is non-volatile and holds firmware.
Virtual memory uses drive space as overflow for RAM — it prevents crashes but is about 1000× slower.
SSDs beat HDDs most dramatically on random access, not on sequential throughput.
RAID provides availability, not backup.

Building a System and Connecting Peripherals

Drain residual power by unplugging and holding the power button for five seconds before opening a case.
A chip can be destroyed by a static charge of about 30 V — far below the ~3000 V you can feel.
PSU rails: +12 V (CPU and GPU, the main load), +5 V and +3.3 V for logic and drives.
Size a PSU with roughly 30% headroom above the measured system draw.
USB-C is a connector shape, not a speed standard.
Hot-swappable: USB, Ethernet, SATA. Never hot-swap: RAM, CPU, PCIe cards.
Motherboard standoffs prevent the board shorting against the case.

Firmware, POST and the Boot Sequence

POST runs before any operating system exists, and reports failures by beeps or LEDs because the display may not work yet.
Firmware hands control to the bootloader, which loads the kernel into RAM; firmware's job then ends.
UEFI replaced legacy BIOS: GPT partitioning, drives over 2 TiB, 128 partitions, and Secure Boot.
Legacy BIOS + MBR is limited to 2 TiB drives and four primary partitions.
A dead CMOS battery causes forgotten settings and a wrong clock, not a dead machine.
Changing SATA mode after installing Windows causes a boot failure, because the storage driver no longer matches.

Operating Systems, File Systems and Maintenance

The OS manages processes, memory, files, devices and security.
On a single core, multitasking is rapid switching, not simultaneous execution.
FAT32 caps a single file at about 4 GB; exFAT and NTFS do not.
Deleting a file removes its directory entry and frees its blocks — the data stays until overwritten.
Never defragment an SSD: it gains nothing and burns write cycles.
3-2-1 backups: three copies, two media types, one off-site — and test a restore.

Unit 3: Networking

Network Types, Topologies and Media

LAN: one site, you own it. WAN: spans sites over infrastructure you do not own.
Client-server centralizes accounts, permissions and backups; peer-to-peer has no central administration.
Star is the standard wired topology; a single cable break affects only one device.
Copper Ethernet is limited to 100 m including patch cables.
Twisting in UTP cancels interference — do not untwist more than about 13 mm at a connector.
Switch ports each get full bandwidth; wireless clients on one access point share it.

The OSI and TCP/IP Models

OSI layers 1–7: Physical, Data link, Network, Transport, Session, Presentation, Application.
Encapsulation unit names: data → segment → packet → frame → bits.
IP addresses stay the same end to end; MAC addresses are rewritten at every hop.
Switch = layer 2 (MAC). Router = layer 3 (IP).
TCP is connection-oriented, acknowledged, ordered and retransmitted; UDP is none of those and therefore faster.
An IP address identifies a machine; a port number identifies a program on it.
Ports to know: 22 SSH, 25 SMTP, 53 DNS, 80 HTTP, 443 HTTPS.

IP Addressing and Subnetting

An IPv4 address is 32 bits, written as four octets of 0–255.
The subnet mask is always contiguous 1s then 0s; /24 = 255.255.255.0.
Usable hosts = $2^{(32 - prefix)} - 2$ .
Network address: all host bits 0. Broadcast address: all host bits 1. Neither is assignable.
Private ranges: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16.
169.254.x.x (APIPA) means DHCP failed.
DHCP sequence: Discover, Offer, Request, Acknowledge (DORA).
IPv6 is 128 bits, written in hex groups, with :: replacing one run of zeros.

Network Devices, Cabling and Security

Hub = layer 1, switch = layer 2 (MAC), router = layer 3 (IP).
A switch learns MAC addresses from the source address of incoming frames, and floods when it does not know a destination.
T568A and T568B differ only by swapping the orange and green pairs.
Straight-through: same standard both ends. Crossover: A on one end, B on the other.
Use WPA3, or WPA2 with AES. Never WEP.
Hidden SSIDs and MAC filtering provide no meaningful security.
Troubleshoot from layer 1 upward: cable, link light, IP address, gateway, internet, DNS.

Unit 4: Electronics and Digital Logic

Voltage, Current, Resistance and Power

$V = I R$ , and its rearrangements $I = V / R$ and $R = V / I$ .
$P = V I = I^{2} R = V^{2} / R$ .
Convert to base units (V, A, Ω) before substituting: 20 mA = 0.020 A, 4.7 kΩ = 4700 Ω.
Voltmeter in parallel; ammeter in series; ohmmeter with the power off.
Mains in Canada is 120 V AC at 60 Hz. Everything in this course is DC.
About 30 mA through the chest can be fatal — current does the harm, voltage drives it.

Components and Schematic Diagrams

Resistor colour code: digit, digit, multiplier, tolerance. Black=0 through White=9.
Gold tolerance band = ±5%; silver = ±10%.
Silicon diode forward drop ≈ 0.7 V; LED forward voltage is 1.8–3.4 V depending on colour.
An LED cannot limit its own current and always needs a series resistor.
Electrolytic capacitors are polarized; ceramic capacitors are not.
A transistor lets a small current control a large one — the basis of every digital switch.
On a schematic, a dot at a crossing means connected; no dot means the wires cross without joining.

Series, Parallel and Voltage Dividers

Series: current is shared, voltages add, resistances add. Total > largest resistor.
Parallel: voltage is shared, currents add, reciprocals add. Total < smallest branch.
Two in parallel: $R_{T} = \frac{R _{1} R _{2}}{R _{1} + R _{2}}$ .
n equal resistors in parallel give $R / n$ .
Voltage divider: $V_{o u t} = V_{in} \times \frac{R _{2}}{R _{1} + R _{2}}$ .
Kirchhoff: voltages around a loop sum to zero; currents into a junction equal currents out.

Logic Gates and Truth Tables

In 5 V logic, above ~2.0 V is logic 1 and below ~0.8 V is logic 0.
AND needs every input true; OR needs at least one; XOR needs the inputs to differ.
A bubble on a gate's output means invert: NAND is AND then NOT.
n inputs give $2^{n}$ truth-table rows.
Half adder: SUM = A ⊕ B, CARRY = A · B.
NAND and NOR are universal — any logic function can be built from either alone.
Never leave a logic input floating; tie unused inputs high or low.

Boolean Algebra and Simplification

$A + A = A$ and $A \cdot A = A$ — there is no 2 in Boolean algebra.
$A + 1 = 1$ , $A \cdot 0 = 0$ , $A + A^{'} = 1$ , $A \cdot A^{'} = 0$ .
Absorption: $A + A \cdot B = A$ .
De Morgan: $(A \cdot B)^{'} = A^{'} + B^{'}$ and $(A + B)^{'} = A^{'} \cdot B^{'}$ .
Inverting an expression inverts each variable AND swaps the operator.
AND binds more tightly than OR, exactly as × binds more tightly than +.
Always verify a simplification with a truth table.

Unit 5: Computer Programming

Variables, Data Types and Input/Output

= assigns a value; == tests equality.
input() always returns a string — wrap it in int() or float() for numbers.
/ gives a float; // gives integer division; % gives the remainder.
"5" + "5" is "55", but 5 + 5 is 10.
Flowchart shapes: oval = start/end, parallelogram = input/output, rectangle = process, diamond = decision.
n % 2 == 0 is the standard test for an even number.

Selection: if, elif and else

if tests a condition; elif is checked only when everything above was False; else catches everything remaining.
In Python, indentation defines the block — it is syntax, not formatting.
and needs both conditions true; or needs at least one.
"Outside a range" uses or; "inside a range" uses and.
An if-elif chain runs at most one branch; separate ifs can all run.
Order an if-elif chain from the most specific condition to the least.
Test at the boundary, one below and one above.

Loops: while and for

Use for when the number of repetitions is known; while when waiting for a condition.
range(n) gives 0 to n−1 — n values. range(a, b) stops before b.
Every while loop needs initialize, test, and update.
Initialize counters and accumulators BEFORE the loop, never inside it.
A nested loop runs the inner loop fully for every pass of the outer loop.
break leaves the loop; continue skips to the next pass.

Lists and Strings

List indexes start at 0; the last valid index is len(list) - 1.
len() gives the number of items; range(len(x)) gives exactly the valid indexes.
append() adds to the end; marks[i] = v replaces an existing item.
for item in list: gives values; for i in range(len(list)): gives indexes.
Strings are immutable — methods return a new string rather than changing the original.
Slices stop before the end index: s[1:4] gives characters 1, 2 and 3.
Always .strip() text input before comparing it.

Functions, Errors and Debugging

A parameter is the name in the definition; an argument is the value passed in the call.
return sends a value back to the caller; print only displays it.
A function with no return returns None.
Local variables exist only inside their function and cannot clash with names outside.
Syntax errors stop the program before it starts; runtime errors stop it mid-run; logic errors do not stop it at all.
Read the LAST two lines of a traceback first.
Test with normal, boundary and invalid inputs.

Unit 6: Computer Interfacing

Microcontrollers and the Arduino

A microcontroller has CPU, memory and I/O on one chip and runs with no operating system.
setup() runs once at power-up; loop() runs forever.
Pin configuration goes in setup(); behaviour goes in loop().
An Uno pin can supply at most 40 mA, and all pins together at most 200 mA.
PWM is available only on pins 3, 5, 6, 9, 10 and 11.
Analog inputs A0–A5 report 0–1023 for 0–5 V.
Serial.begin(9600) plus Serial.println() is how you debug a sketch.

Digital Input and Output

An unconnected input floats and reads random values — every button needs a pull-up or pull-down resistor.
Pull-down: resistor to ground, button to 5 V, resting LOW. Pull-up: resistor to 5 V, button to ground, resting HIGH.
INPUT_PULLUP uses the chip's internal resistor, so pressed reads LOW.
10 kΩ is the standard pull resistor value: defines the level firmly, wastes only 0.5 mA.
Switch bounce produces multiple transitions from one press — debounce in software or hardware.
delay() blocks everything; millis() lets you time without blocking.

Analog Inputs and Sensors

The Uno's ADC is 10-bit: $2^{10} = 1024$ levels, reported as 0–1023 across 0–5 V.
$V = \frac{reading \times 5.00}{1023}$ , and one step is about 4.9 mV.
Use 5.0 and 1023.0 in C, or integer division silently returns 0.
A resistive sensor needs a voltage divider, because an analog pin measures voltage, not resistance.
Choose the fixed resistor near the middle of the sensor's resistance range for maximum sensitivity.
A TMP36 gives 10 mV per °C with a 500 mV offset.
Never apply more than 5 V to an analog input.

PWM, Motors and Control Systems

PWM switches a digital pin rapidly; duty cycle sets the average voltage.
analogWrite(pin, value) takes 0–255. $V_{a vg} = \frac{value}{255} \times 5$ .
PWM is available only on pins 3, 5, 6, 9, 10 and 11 on an Uno.
A motor needs a transistor (for current) and a flyback diode (for the inductive spike).
An H-bridge reverses a motor; closing both switches on one side causes destructive shoot-through.
A servo reads pulse WIDTH: 1.0 ms = 0°, 1.5 ms = 90°, 2.0 ms = 180°, repeated every 20 ms.
Separate supplies must share a common ground.
Closed loop measures the result and corrects; open loop does not.

Unit 7: Technology, Environment, Society and Careers

Environmental Impact and E-Waste

Manufacturing a laptop usually consumes more energy than it will use in its working life.
Embodied energy is everything spent before the product reaches the user.
E-waste contains lead, mercury, cadmium and brominated flame retardants — all hazardous.
It also contains gold, silver, copper and palladium in higher concentrations than natural ore.
RoHS restricts hazardous substances; WEEE makes producers fund recycling; Energy Star certifies efficiency.
The hierarchy is reduce, reuse, repair, recycle, dispose — in that order.
Wipe or destroy a drive before disposal; deletion does not remove the data.

Societal Impact, Ethics and Security

The digital divide covers access, affordability, connection quality, literacy and accessibility.
PIPEDA governs private-sector handling of personal information in Canada.
Copyright is automatic on creation; patents must be applied for.
Open-source software is licensed, not unowned — MIT is permissive, GPL is copyleft.
The CIA triad: Confidentiality, Integrity, Availability.
Most successful attacks exploit vulnerabilities that already had patches.
Unauthorized access to a computer system is a criminal offence in Canada, regardless of intent.

Workplace Safety, Standards and Careers

Unplug and hold the power button for five seconds before opening a case.
Never open a power supply or CRT monitor — their capacitors hold lethal charge.
ESD damages chips at around 30 V; you cannot feel a charge below about 3000 V.
WHMIS 2015 has three parts: labels, Safety Data Sheets and worker training.
A soldering iron runs at about 350 °C and looks the same hot or cold — always use the stand.
Ontario OHSA gives every worker the right to know, to participate, and to refuse unsafe work.
Technician = 2-year diploma; technologist = 3-year diploma; P.Eng. = accredited degree plus licence.