IGCSE Computer Science (0478) · Paper 1 — Computer Systems
Data Representation
Binary and hexadecimal number systems, text/sound/image representation and data storage sizing show up as short-answer conversions on Paper 1 — the marks are won or lost on method, not just the final number.
1.1 Number systems
- Understand how and why computers use binary to represent all forms of data.
- Understand the denary, binary and hexadecimal number systems.
- Convert between positive denary and positive binary, positive denary and positive hexadecimal, and positive hexadecimal and positive binary (max 16-bit).
- Understand how and why hexadecimal is used as a beneficial method of data representation.
- Add two positive 8-bit binary integers.
- Understand the concept of overflow and why it occurs in binary addition.
- Perform a logical binary shift (left, right, multiple) on a positive 8-bit binary integer and understand the effect this has on the value.
- Use the two's complement number system to represent positive and negative 8-bit binary integers, converting to and from binary/denary.
1.2 Text, sound and images
- Understand how and why a computer represents text and the use of character sets, including ASCII and Unicode.
- Understand how and why a computer represents sound, including the effects of the sample rate and sample resolution.
- Understand how and why a computer represents an image, including the effects of the resolution and colour depth.
1.3 Data storage and compression
- Understand how data storage is measured, from bit through nibble, byte, KiB, MiB, GiB, TiB, PiB to EiB.
- Calculate the file size of an image file and a sound file, using given resolution, colour depth, sample rate, sample resolution or track length (using 1024, not 1000).
- Understand the purpose of and need for data compression.
- Understand how files are compressed using lossy and lossless compression methods, e.g. run length encoding (RLE).
Practice this topic
ExamEdge generates fresh, exam-authentic data representation questions, marks every answer, and tells you exactly why a mark was lost — concept gap, reading load, or answer format.