Chapter 3 #5

Question 1

Module 1: Computer Hardware

Question 2

What is internal memory?

Answer 2

Internal memory includes components that are close to the processor, like registers (internal to the processor) or memory cache (external to the processor).

Question 3

What is memory cache?

Answer 3

It is used to store data that the processor will likely need again.

Question 4

What is primary memory?

Answer 4

Part of the computer memory directly accessed from the CPU.
Contains RAM and ROM.

Question 5

What is the primary functional difference between RAM and ROM?

Answer 5

RAM (Random Access Memory) is volatile memory, stores data that is currently being used in applications or services; its contents are lost when power is cut.
ROM (Read-Only Memory) is non-volatile and stores permanent startup instructions, such as the start up instructions, OS kernel, or BIOS.

Question 6

Detail the differences between Dynamic RAM (DRAM) and Static RAM (SRAM) regarding construction and performance.

Answer 6

1. DRAM is constructed from transistors and capacitors that require a constant power to retain data, whereas SRAM uses flip-flops to hold each bit of memory.
2. SRAM is significantly faster than DRAM, making SRAM ideal for the memory cache while DRAM is used for main RAM modules.
3. DRAM is volatile, while SRAM is non-volatile
4. DRAM is less expensive to manufacture per unit storage, consumes less power, and has a higher memory capacity, storing more bits per chip than SRAM (higher memory density).

Question 7

What is the specific utility of SRAM in modern processors?

Answer 7

Due to its high speed and lack of a refresh requirement, SRAM is used for processor memory cache.

Question 8

Define the three programmable variants of ROM.

Answer 8

1. PROM: Programmable once by burning internal fuses with an electric current.
2. EPROM: Can be reset and rewritten using ultraviolet (UV) light.
3. EEPROM: Can be erased and written repeatedly using pulsed voltages.

[Past Exam Q&A adds:]
• EPROM needs to be removed from the device to be erased; EEPROM can be erased in situ.
• EPROM must be entirely erased before rewriting; EEPROM does not have to be entirely erased before rewriting.

Question 9

What is the technical classification of Flash memory?

Answer 9

Flash memory is a type of EEPROM specifically engineered for high-density storage applications like SSDs, memory cards, and memory sticks.

Question 10

What is secondary storage?

Answer 10

They are non-volatile storage devices not directly accessible by the CPU.
They have larger capacities than RAM and ROM.
They store all of the operating system, applications, files, device drivers.

Question 11

Describe the classification and physical data organization on a Hard Disk Drive (HDD).

Answer 11

HDD is a type of magnetic storage device.
Data is organized into concentric tracks which are further divided into sectors.
The platters are mounted on a central spindle and rotate at several thousand revolutions per minute.

Question 12

Define “latency” and “fragmentation” as they pertain to HDD performance.

Answer 12

Latency is the time taken for a specific sector to rotate under the read-write head.
Fragmentation occurs when files are stored in non-adjacent sectors, forcing the actuator arm to move excessively to retrieve data.

Question 13

What are the primary advantages of SSDs over HDDs?

Answer 13

SSDs have no moving parts, resulting in near-instantaneous startup.
SSDs have lower power consumption, higher physical resilience to shock, and much lower latency.

Question 14

Module 2: Optical and External Storage Devices

Question 15

Compare between the different types of optial storage in terms of light used, number layers coded, and max capacities (aprox).

Answer 15

1. CD: Uses red light, coded on one layer only (single), max capacity of about 700MB
2. DVD: Uses red light, but of a different wavelength, coded on two layers (double), max capacity of about 8-9GB
3. Blueray: Uses blue light, can be coded on one or two layers, max capacity of about 512GB

Question 16

How is data read from optical media like CDs and DVDs?

Answer 16

A low-power laser reflects off a metal layer; “lands” reflect light directly back to a photodiode, while “pits” scatter the light. This pattern is interpreted as binary data. Pit = 1, Land = 0.

Question 17

Module 3: Embeded Systems

Question 18

What are the primary characteristics of Embedded Systems?

Answer 18

1. They are computer systems with a dedicated function within a larger mechanical or electronic device.
2. They often use microprocessors for efficient, specific operations.

They are found in industrial, automotive, and home appliance applications.

Question 19

List three “Pros” and three “Cons” of Embedded Systems.

Answer 19

Pros: Small size, low manufacturing cost, and low power consumption.
Cons: Difficult to upgrade, requires specialist troubleshooting, and potential confusing user interfaces or vulnerability to hackers.

Question 20

Module 4: Peripheral and Inupt/Output Devices

Question 21

Detail the operation of a keyboard.

Answer 21

1. When a key is presssed it presses a switch
2. A circuit is closed.
3. The ROM contains a character map (lookup table with all characters and locations).
4. Microprocessor compares the location of the pressed switch with the ROM’s character map to identify key pressed.

Question 22

Detail the operation of a scanner.

Answer 22

1. Light is emitted and bounces back off the document.
2. Reflected light falls on to mirrors.
3. Mirrors reflect refflected light back to CCD sensors.
4. Light is turnned into voltage based on light intensity.
5. The brighter the reflected light the higher voltage detected for the image document.

Question 23

How does an optical mouse calculate movement coordinates?

Answer 23

An LED reflects light off the surface into a CMOS sensor that captures approximately 1,500 images per second; a microprocessor analyses the differences in surface patterns between images to calculate movement.

Question 24

Explain the conversion steps in a dynamic microphone.

Answer 24

1. Sound waves vibrate a diaphragm attached to a wire coil.
2. The coil moves past a permanent magnet to induce an electrical current.
3. Which is then sampled and digitized by an ADC.

[Past Exam Q&A adds:]
Full exam answer:
• The microphone has a diaphragm / ribbon.
• The incoming sound waves cause vibrations of the diaphragm.
• Causing a coil to move past a magnet (dynamic microphone) // changing the capacitance (condenser microphone) // deforms the crystal (crystal microphone).
• An electrical signal is produced.

Question 25

Compare resistive and capacitive touchscreen mechanics.

Answer 25

1. Resistive screens use two layers, seperated by a thin space, that close a circuit when a user presses the top layer and causes the layers to touch. The horizontal and vertical position is transmted to the processor. 2. Capacitive screens use a glass layer that stores charge. A change (decrease) in the electric field is detected when a conductive finger touches the surface. The coordinates where the decrease in charge occurs is calculated and sent to the processor.

Question 26

Distinguish between the two types of inkjet printing technology.

Answer 26

Thermal bubble technology uses transistors to produce heat to vaporise ink into a bubble that ejects as a droplet out of the print head. Piezoelectric technology uses a crystal that vibrates when given a charge (piezocrystal) to force ink through the nozzle when a charge is supplied.

Question 27

What are the types of different screens?

Answer 27

1. LCD and LED backlit screens. 2. OLED (Organic LED): Made out of carbon compounds. Generates its own light, no backlighting required.

Question 28

Define Sensors, Analogue Data, Digital Data.

Answer 28

1. Sensors: They are input devices that measure physical properties, and generate analogue data. An ADC is required to digitise the data. 2. Analogue Data/Signals: Continous data that contains an infinite range of values. 3. Digital Data: Discrete data that only has two values (0 and 1).

Question 29

What is the fundamental difference between monitoring and control systems?

Answer 29

Monitoring systems passively observe and record data, alerting humans if parameters are exceeded. Control systems use actuators and feedback loops to actively adjust the environment automatically.

Question 30

What is an actuator and what is its role?

Answer 30

An actuator is an output device (like a motor, heater, or valve) that carries out physical actions based on signals from a microprocessor in a control system.

Question 31

Describe the four-wire design of a USB cable.

Answer 31

Two wires are utilised for power and earth/ground, while the other two wires are dedicated to data transmission.

Question 32

Which hardware components are essential for a VR headset's 3D immersion?

Answer 32

Dual high-resolution LCD/OLED screens, lenses to reshape focus for 3D effect, an accelerometer to detect head movement, and spatial audio speakers.

Question 33

Identify the sensor type and application for the following needs: soil acidity and vehicle deceleration.

Answer 33

Soil acidity is measured by a pH sensor (chemical monitoring). Vehicle deceleration is measured by an accelerometer (airbag deployment).

Question 34

How do active and passive infrared sensors differ in operation?

Answer 34

Active infrared sensors detect a break in an emitted beam. Passive infrared (PIR) sensors measure heat radiation given off by objects (e.g., body heat).

Question 35

Module 5: Extra Missing Information

Question 36

Describe the mechanics of dual-layering in optical discs.

Answer 36

Dual-layering involves using two distinct recording layers on a single side of a DVD, significantly increasing the total storage capacity.

Question 37

How is data physically written to a CD-RW (Re-Writable) disc?

Answer 37

A high-powered laser heats the metallic layer to different temperatures to create amorphous or crystalline states. These states result in different reflectivity levels representing binary 1s and 0s. (Lands and Pits)

Question 38

Explain the two specific technologies used in 3D Printing.

Answer 38

1. Direct 3D Printing: Uses an inkjet-like head moving in x, y, and z directions to build layers of melted material. 2. Binder 3D Printing: Uses a two-stage pass where dry powder is spread and then a liquid binding agent is applied to solidify the pattern.

Question 39

Describe the "Surface Acoustic Wave" (SAW) touchscreen method.

Answer 39

Transducers are placed on the x and y axes to send ultrasonic waves across the glass. Reflectors detect disturbances in these waves caused by a user's touch and send the data back to calculate coordinates.

Question 40

Describe the continuous procedural steps of a Control System.

Answer 40

1. Sensors send data to a microprocessor via an ADC. 2. Microprocessor compares data to stored values. 3. If different, a signal is sent to an actuator to take physical action. 4. This creates a feedback loop where the environment is sensed as new input.

Question 41

What is the main functional difference between an Event-driven and a Time-driven control system?

Answer 41

An event-driven system alters its state in response to a specific event (e.g., a sensor trigger), while a time-driven system takes action at specific, predetermined points in time.

Question 42

List four benefits of using sensors over human monitoring.

Answer 42

Sensors can work 24/7 without exhaustion, avoid human error, operate in dangerous environments, and detect errors/changes instantly to maintain consistent conditions.

Question 43

What occurs immediately when a USB device is plugged into a computer?

Answer 43

1. The computer automatically detects the device. 2. The device is recognised. 3. The appropriate Device Driver is loaded. 4. If missing, the user is prompted to download it.

Question 44

Module 6: Classified Questions

Question 45

Describe how a single page is printed on a laser printer (7 steps).

Answer 45

1. A laser beam and a rotating mirror are used to draw an image of the page on the photosensitive drum. 2. The image is converted on the drum into an electrostatic charge. 3. Electrostatic charge attracts toner. 4. The charged paper is rolled against the drum. 5. The oppositely charged paper picks up the toner particles from the drum. After picking up the toner, the paper is discharged to stop it clinging to the drum. 6. The paper passes through a fuser, which heats up the paper. The toner melts and forms a permanent image on the paper. 7. The electrical charge is removed from the drum, and the excess toner is collected.

Question 46

Describe the basic internal operation of a 3D printer works (9 steps).

Answer 46

1. The object is designed in Computer Aided Design (CAD) software. 2. The software splits the object into slices. 3. The data about the slices is sent to the printer. 4. The solid plastic is melted and transferred to the nozzle. 5. A stepper motor moves the nozzle into position. 6. The nozzle extrudes the molten plastic. 7. The steps 5 to 6 repeat until the layer is complete. 8. A fan cools the layer. 9. The steps 4 to 8 are repeated for each subsequent layer.

Question 47

Describe the internal operation of a speaker (7 steps).

Answer 47

1. An electric current is sent to the speaker. 2. The electric current passes through the coil. 3. The current in the coil creates an electromagnetic field. 4. Changes in the audio signal cause the direction of the electrical current to change. This determines the polarity of the electromagnet. 5. The electromagnet is repelled by or attracted to the permanent magnet. 6. The movement of the coil causes the diaphragm to vibrate. 7. The vibration creates sound waves.

Question 48

Compare between RAM and ROM.

Answer 48

1. RAM is volatile while ROM is non-volatile. 2. RAM can change while ROM (usually) can’t be changed. 3. ROM is read only, RAM is read/write.

Question 49

State the advantages of SSD and HDD.

Answer 49

Hard disk drive (HDD): 1. less expensive per unit storage.. 2. Larger storage capacity than the flash drive. 3. Has more longevity. Solid state drive (SSD): 1. No moving parts, more reliable. 2. Lower power consumption than HDDs, runs cooler. 3. Robust. 4. Low latency.

Question 50

Describe solid state memory.

Answer 50

Solid state memory has no moving parts and is non-volatile. It makes use of arrays of NAND and NOR gates to store data. SSD controller manages these components. Solid state memory uses a grid of columns and rows that has two transistors at each intersection. One transistor is called the floating gate (stores the charge) and the other is called the control gate (controls the flow of charge). Memory cells store voltages which can represent either a 0 or a 1.

Question 51

Describe the physical structure, operation, and performance characteristics of a Hard Disk Drive (HDD).

Answer 51

1. The HDD is a magnetic storage device that uses spinning platters divided into tracks and sectors, rotating at very high speeds. 2. To access data, the operating system spins the platter and the read-write head moves to the correct track, detecting changes in magnetic fields to represent data. 3. Performance is affected by latency—the time taken for the correct sector to rotate under the head—and data access is sequential within a given sector. 4. Over time, files can become fragmented if sectors are not adjacent, which degrades performance unless addressed by defragmentation software. 5. HDDs are non-volatile secondary storage with larger capacities than RAM, and they can be internal or external/portable via USB for backups. [Past Exam Q&A adds:] Read/write mechanism (from exam Q&A): • When writing to disk: a variation in the current in the read/write head produces a variation in the magnetic field on the disk. • When reading from disk: a variation in the magnetic field produces a variation in current through the read/write head. • The hard disk has one or more platters; each surface is ferrous oxide capable of being magnetised. • The entire mechanism is contained inside a sealed (aluminium) box. • The surface of the platter is divided into concentric tracks and then into sectors; one track in one sector is the basic unit of storage, called a block.