O Level Free Diagnostic

Data Representation

1Which statement best describes Binary and hexadecimal?

ACharacter sets assign numeric codes to characters. Unicode supports far more scripts and symbols than ASCII because it uses a much larger code space.BA bitmap stores a grid of pixels. Resolution controls the number of pixels and colour depth controls the number of bits available for each pixel.CAn analogue wave is sampled at regular intervals. A higher sample rate and sample resolution improve fidelity but increase file size.DBinary uses base 2 and hexadecimal uses base 16. One hexadecimal digit represents exactly four binary bits, making long bit patterns easier to read.

Communication

2Which statement best describes Simplex, half-duplex and full-duplex?

ASimplex is one-way only, half-duplex allows both directions but not at the same time, and full-duplex carries both directions simultaneously.BSynchronous transmission uses shared timing and continuous blocks; asynchronous transmission uses start and stop bits around smaller units.CParity checks, checksums and echo checks can reveal corrupted data. Automatic repeat requests ask for damaged or missing data again.DA message is divided into addressed packets that can take different routes and are reordered at the destination.

Storage Devices

3Which statement best describes Solid-state storage?

AHard disk drives magnetise areas on rotating platters and use a moving read/write head. They offer high capacity at low cost but contain moving parts.BFlash memory stores charge electronically and has no moving parts, making it fast, quiet and resistant to shock.CPrimary memory is directly accessed by the processor; secondary storage provides non-volatile, long-term capacity.DA justified choice weighs capacity, access speed, reliability, portability, compatibility and cost for the stated user.

Computer Architecture

4Which statement best describes Buses?

AThe control unit coordinates operations, the arithmetic logic unit performs calculations and logical tests, and registers hold small working values.BThe PC holds the next instruction address, MAR holds a memory address, MDR holds transferred data, CIR holds the current instruction and ACC stores intermediate results.CThe address bus carries locations, the data bus carries data and instructions, and the control bus carries command and timing signals.DClock speed, cache size, number of cores and instruction design influence performance, but the program and workload determine the real benefit.

Input and Output Devices

5Which statement best describes Device selection?

AKeyboards, pointing devices and touchscreens let people deliberately enter data or commands. Accuracy and accessibility depend on the context.BBarcode readers, QR readers, RFID and optical readers capture encoded data quickly with less transcription error.CSensors measure properties such as temperature, pressure, light or moisture and send data to a processor, often through an analogue-to-digital converter.DSuitability depends on environment, data type, speed, accuracy, accessibility, durability and total cost.

Network Hardware

6Which statement best describes Network interface card?

AA switch connects devices within a LAN and forwards a frame only toward the port associated with its destination MAC address.BA router connects different networks and forwards packets using destination IP addresses and routing information.CA WAP allows wireless devices to join a wired network by transmitting and receiving radio signals.DA NIC connects a device to a network and provides a hardware address used for local communication.

Software

7Which statement best describes Operating system?

AAn OS manages memory, processes, files, peripherals, security and the user interface while providing a platform for applications.BUtilities perform maintenance or protection tasks such as backup, compression, encryption, anti-malware scanning and disk management.CAssemblers translate assembly language, compilers translate a whole high-level program, and interpreters translate and execute one statement at a time.DAn IDE combines editing, translation, execution and debugging features such as syntax highlighting, breakpoints and diagnostics.

Internet

8Which statement best describes URLs and protocols?

AThe internet is the interconnected network; the web is a collection of linked resources requested with HTTP or HTTPS through a browser.BA URL identifies a resource and can include scheme, host, path and query. Protocols define the rules used to transfer data.CMalware, phishing, pharming, brute-force attacks, denial of service and interception threaten confidentiality, integrity or availability.DEncryption, authentication, firewalls, access rights, updates and user education work together as layered security.

Automated Systems

9Which statement best describes Feedback loop?

ASensors collect measurements from the environment and may require analogue-to-digital conversion before processing.BThe processor compares a reading with stored rules or a target and decides whether an output must change.CThe output changes the environment, sensors measure the new condition and the cycle repeats so the system can correct itself.DAutomation can improve speed, consistency and safety but brings cost, maintenance, job impact and failure risks.

Robotics

10Which statement best describes Social impact?

AA robot is programmable, can sense or respond to its environment and can carry out physical actions through effectors or actuators.BSensors gather environmental data while effectors such as grippers, wheels or joints allow the robot to act.CAutonomous robots make control decisions from programming and sensor data; remote systems depend on commands from a human operator.DRobotics can improve safety and productivity while affecting employment, privacy, accountability and the skills people need.