Answer

Given Data

• Octal number to convert: $(366)_8$
• Binary subtraction: $(1110111)_2 - (1001111)_2$

(a) Convert $(366)_8$ to Hexadecimal

Method: Octal → Binary → Hexadecimal

Step 1: Each octal digit to 3-bit binary

$$(366)_8 = (011,110,110)_2 = (011110110)_2$$

Step 2: Group into 4 bits from the right

The nine bit string is padded on the left to a whole number of four bit groups before grouping, so the leading group is $0000$ and not $0001$:

$$011110110 \rightarrow 0000\ 1111\ 0110$$

Step 3: Convert each group to hex

$$\boxed{(366)8 = (F6){16}}$$

Verify: $(366)8 = 3\cdot64 + 6\cdot8 + 6 = 192 + 48 + 6 = 246$ and $(F6){16} = 15\cdot16 + 6 = 240 + 6 = 246$, so the two agree. ✓

(b) Subtract $(1001111)_2$ from $(1110111)_2$

Compute $(1110111)_2 - (1001111)_2$.

Method: 2's Complement Subtraction

Step 1: 2's complement of $(1001111)_2$

• 1's complement: $0110000$
• Add 1: $0110000 + 1 = 0110001$

Step 2: Add minuend and 2's complement

$$ \begin{array}{r} 1110111 \ +\ 0110001 \ \hline 10101000 \end{array} $$

Step 3: Discard the carry (leftmost 1)

$$\text{Result} = (0101000)_2$$

Verification (decimal):

• $(1110111)_2 = 64+32+16+4+2+1 = 119$
• $(1001111)_2 = 64+8+4+2+1 = 79$
• $119 - 79 = 40$
• $(0101000)_2 = 32 + 8 = 40$ ✓

$$\boxed{(1110111)_2 - (1001111)_2 = (0101000)_2 = 40}$$

Summary

• $(366)8 = (F6){16}$
• $(1110111)_2 - (1001111)_2 = (0101000)_2$

Computer Bus and Working of Laser Printer

Computer Bus [1 Mark]

A computer bus is a communication system (set of physical wires/lines) that transfers data, addresses, and control signals between the components of a computer system (such as CPU, memory, and I/O devices).

Note: Reference notes were not available for this topic; answer is based on standard CS curriculum.

Working of a Laser Printer [4 Marks]

A laser printer is a high-quality, high-speed output device that uses a laser beam and electrostatic technology to produce text and images on paper. Its working involves the following steps:

Step 1: Processing (RIP - Raster Image Processing)

• The computer sends the document data to the printer.
• The printer's controller converts the data into a bitmap image (a dot-by-dot representation of the page).

Step 2: Charging

• A primary corona wire (or charge roller) applies a uniform negative electrostatic charge to the surface of the photosensitive drum (photoconductor drum).

Step 3: Exposing (Writing with Laser)

• A laser beam is directed onto the drum through a rotating mirror.
• Wherever the laser hits, the negative charge is neutralized (discharged), creating an invisible electrostatic image (latent image) on the drum.
• Areas hit by the laser become relatively positively charged compared to unexposed areas.

Step 4: Developing (Toner Application)

• Toner (fine, negatively charged black or colored powder) is applied to the drum.
• The toner is attracted to the discharged (laser-hit) areas of the drum, making the latent image visible.

Step 5: Transferring

• A sheet of paper is fed from the paper tray.
• A transfer corona wire gives the paper a positive charge.
• The negatively charged toner on the drum is attracted to the paper, transferring the image onto it.

Step 6: Fusing

• The paper passes through the fuser unit, which consists of heated rollers.
• Heat and pressure melt and bond the toner permanently onto the paper.
• The printed page exits the printer.

Step 7: Cleaning

• Any residual toner remaining on the drum is removed by a cleaning blade.
• The drum is discharged and made ready for the next page.

Summary Diagram (Flow)

Processing → Charging → Exposing → Developing → Transferring → Fusing → Cleaning

Key Advantages of Laser Printer

• High speed and high resolution
• Sharp, clear text and graphics
• Suitable for high-volume printing

Short Notes

a) Societal Impacts of IT

Information Technology (IT) has profoundly transformed modern society across multiple dimensions:

Positive Impacts:

• Communication: IT has revolutionized communication through email, social media, video conferencing, and instant messaging, making global communication faster and cheaper.
• Education: E-learning platforms, online courses, and digital libraries have made education more accessible to people worldwide.
• Healthcare: Electronic health records, telemedicine, and medical imaging technologies have improved diagnosis and patient care.
• Economy: IT has created new industries, enabled e-commerce, and increased productivity across all sectors.
• Employment: New job categories such as software developers, data analysts, and cybersecurity experts have emerged.

Negative Impacts:

• Privacy Concerns: Mass data collection and surveillance raise serious privacy issues.
• Digital Divide: Unequal access to technology creates social and economic inequality.
• Cybercrime: Hacking, identity theft, and online fraud have increased.
• Job Displacement: Automation and AI are replacing traditional jobs.
• Social Isolation: Excessive screen time and social media use can reduce face-to-face interaction.

b) Internet of Things (IoT)

Definition: The Internet of Things (IoT) refers to the network of physical devices, vehicles, appliances, and other objects embedded with sensors, software, and connectivity that enables them to collect and exchange data over the internet without requiring human-to-human or human-to-computer interaction.

Key Characteristics:

• Connectivity between devices
• Automation and control
• Real-time data collection and analysis
• Scalability

Components of IoT:

• Sensors/Devices: Collect data from the environment (e.g., temperature sensors, cameras)
• Connectivity: Data is transmitted via Wi-Fi, Bluetooth, or cellular networks
• Data Processing: Cloud or edge computing processes the collected data
• User Interface: Results are communicated to the end user via apps or dashboards

Applications of IoT:

Advantages:

• Improved efficiency and automation
• Better decision making through real-time data
• Cost savings and resource optimization

Disadvantages:

• Security and privacy vulnerabilities
• High implementation cost
• Complexity in managing large networks of devices