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← Unit 1: Introduction to Computers

TEJ3M · Unit 1 test review

Introduction to Computers: Test Review

Everything for the Unit 1 test on one page: the key facts from all 4 lessons, the mistakes that cost the most marks, and a practice test that points you back to the lessons you need.

Key facts

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: — doubling each time.
  • An -bit number can represent different values, from to .
  • One byte = 8 bits = values 0 to 255 = exactly two hex digits.
  • Four bits = one hex digit, always. 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.
  • -bit colour depth gives 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.

Where marks get lost

  • Calling RAM "storage" — RAM is volatile working memory in the process stage, not where files live. (The Computer System Model)
  • Classifying a monitor as input because you look at it. Classification follows the direction data travels, not where you are standing. (The Computer System Model)
  • Thinking a hard drive is part of the CPU. The CPU cannot read a drive directly; it requests data through a controller. (The Computer System Model)
  • Assuming firmware is hardware because it lives on a chip — it is still instructions, and it can be updated. (The Computer System Model)
  • Forgetting that a touchscreen, network card or modem is both input and output. (The Computer System Model)
  • Reading division-method remainders top-to-bottom instead of bottom-to-top, which reverses the whole answer. (Binary, Decimal and Hexadecimal)
  • Splitting a binary number into nibbles from the LEFT. Always group in fours starting from the right, padding the left with zeros. (Binary, Decimal and Hexadecimal)
  • Writing and then claiming the largest 8-bit value is 256. It is 255, because counting starts at 0. (Binary, Decimal and Hexadecimal)
  • Treating hex letters as variables. In , B is the digit 11, not an unknown. (Binary, Decimal and Hexadecimal)
  • Converting binary to hex by going through decimal — it works but wastes time and invites arithmetic errors. (Binary, Decimal and Hexadecimal)
  • Forgetting the factor of 8 when a file size (bytes) meets a link speed (bits per second). (Representing Data: Bits, Bytes and Files)
  • Multiplying an image's pixel count by the colour depth and calling the result bytes — it is bits until you divide by 8. (Representing Data: Bits, Bytes and Files)
  • Assuming 1 MB = 1024 KB in a question that defines 1 MB = 1 000 000 bytes. Use the definition the question gives. (Representing Data: Bits, Bytes and Files)
  • Thinking a drive that reports less capacity than advertised is faulty or has hidden partitions — it is the kB/KiB labelling difference. (Representing Data: Bits, Bytes and Files)
  • Believing lossy compression can be undone by re-saving at higher quality. The discarded detail is gone permanently. (Representing Data: Bits, Bytes and Files)
  • Stating Moore's law as "computer speed doubles every two years" — it is about transistor count on an economically produced chip. (Generations, Moore's Law and Where Hardware Is Going)
  • Calling Moore's law a law of physics. It is an observation about manufacturing economics, and it is slowing. (Generations, Moore's Law and Where Hardware Is Going)
  • Assuming more cores automatically means faster programs. Single-threaded code gains nothing from extra cores. (Generations, Moore's Law and Where Hardware Is Going)
  • Mixing up the generations by naming the computer instead of the switching technology — the technology is what defines each one. (Generations, Moore's Law and Where Hardware Is Going)
  • Thinking clock speed alone ranks two CPUs. Core count, cache size, instructions per cycle and architecture all matter. (Generations, Moore's Law and Where Hardware Is Going)

Practice test

24 questions from across the unit. Each one shows the lesson it comes from.

  1. The Computer System Model
    1
    Which component belongs to the PROCESS stage rather than to input, output or storage?
  2. The Computer System Model
    2
    Which of these is firmware?
  3. The Computer System Model
    3
    Put these in the order data flows through a system that reads a barcode and prints a receipt.
    1. 1CPU looks up the price
    2. 2Printer produces the receipt
    3. 3Price is saved to the sales database
    4. 4Barcode scanner reads the label
  4. The Computer System Model
    4
    Match each component to its stage.
    Microphone
    Arithmetic logic unit
    Servo motor
    microSD card
  5. The Computer System Model
    5
    You lose an unsaved essay in a power cut. Which property of RAM explains this?
  6. The Computer System Model
    6
    A computer has 16 GB of RAM and a 1 TB SSD (1 TB = 1000 GB). How many times larger is the storage than the RAM?
  7. Binary, Decimal and Hexadecimal
    7
    Convert to decimal.
  8. Binary, Decimal and Hexadecimal
    8
    Convert to 8-bit binary.
  9. Binary, Decimal and Hexadecimal
    9
    How many distinct values can 6 bits represent?
  10. Binary, Decimal and Hexadecimal
    10
    What is the largest value that can be stored in 10 bits?
  11. Binary, Decimal and Hexadecimal
    11
    Match each 4-bit group to its hex digit.
    1010
    1100
    0111
    1111
  12. Binary, Decimal and Hexadecimal
    12
    A student converts by dividing by 2 and writes the remainders as 1, 0, 1, 1, 0, 1 reading downwards. What is the correct binary answer?
  13. Representing Data: Bits, Bytes and Files
    13
    An image is 800 × 600 pixels at 16-bit colour. What is its size in bytes?
    bytes
  14. Representing Data: Bits, Bytes and Files
    14
    A drive is sold as 2 TB but Windows reports 1.82 TB. What is the explanation?
  15. Representing Data: Bits, Bytes and Files
    15
    How many distinct colours can a pixel with 8-bit colour depth display?
  16. Representing Data: Bits, Bytes and Files
    16
    A file is compressed and later restored byte-for-byte identically. What type of compression was used?
  17. Representing Data: Bits, Bytes and Files
    17
    Why does a photo of a blue sky compress to a much smaller JPEG than a photo of gravel, at the same resolution?
  18. Representing Data: Bits, Bytes and Files
    18
    How many bits are in 3 KiB? (1 KiB = 1024 bytes)
    bits
  19. Generations, Moore's Law and Where Hardware Is Going
    19
    Which statement of Moore's law is correct?
  20. Generations, Moore's Law and Where Hardware Is Going
    20
    A CPU manufacturer adds more cores rather than raising clock speed. What is the main reason?
  21. Generations, Moore's Law and Where Hardware Is Going
    21
    What name is given to the growing gap between CPU speed and RAM speed?
  22. Generations, Moore's Law and Where Hardware Is Going
    22
    Which workload benefits LEAST from upgrading from a 4-core to a 16-core CPU?
  23. Generations, Moore's Law and Where Hardware Is Going
    23
    Why is it becoming physically difficult to keep shrinking transistors?
  24. Generations, Moore's Law and Where Hardware Is Going
    24
    Match each trend to its description.
    Cloud computing
    Edge computing
    Internet of Things
    Quantum computing

Endless drill

Fresh numbers every time, for the calculation questions in this unit.

Endless drillnew numbers every time

Generating a problem…

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