1. Information Representation
Number systems, BCD, two's complement, character sets, multimedia (bitmap/vector, sound) and file compression.
Statometer87BankerNext Paper 195%Everything for this topic — study hub
AS Level · 9618 · Paper 1
This topic is rows 1–4 of the study route.Open it on your study route
Statometer — what 33 real papers say about this topic and each of its 4 syllabus bullets
Banker · #4 of 12 in AS Level · recomputed with every new session
Set in nearly every paper and worth a big slice of it — revise first, expect it.
- Next Paper 1
- 95%
- 9 in 10 chance it is set
- Marks a paper
- 20.1 / 75
- 27% of Paper 1 · fair share 13%
- Appeared in
- 33 / 33
- Paper 1 sittings 2021–2026
- Last set
- May/Jun 2026
- 9618/13 · Q8 · 10 marks · 11-series streak
What the papers say
- Set in 33 of 33 Paper 1 sittings on the current syllabus — treat it as certain.
- Worth about 20.1 marks a paper (27% of Paper 1, 2.1× its fair share).
- Last set May/Jun 2026 · 9618/13 · Q8 for 10 marks — in the most recent series.
- Set in each of the last 11 series without a miss.
- Steady at around 21 marks a paper year on year.
- Lives on “Describe” and “Explain” — 70% of its questions: full sentences with a reason, not one-word answers.
- 37% of its questions involve a diagram, table or figure — practise with pen and paper.
- 43% of its questions are set out as code, pseudocode or a table to complete.
- Its biggest question so far: 18 marks (May/Jun 2024 · 9618/11 · Q2).
- Inside the topic, §1.2 Multimedia carries the most marks (50%) and §1.1 Binary arithmetic the least (10%).
- It is examined mostly as AO1 (Knowledge & understanding, 62%), the rest AO2 (38%) — definitions and descriptions in syllabus words score.
- The examiner has commented on 90 of its questions — read “What the examiner said” before you practise.
- The single biggest share of Paper 1 among its 8 topics.
Command words
Share of questions using the word (a question can use several). What each wants →
Question shapes
- ≤ 6 mk34
- 7–9 mk44
- 10–12 mk19
- 13–15 mk22
- 16+ mk12
Average 9.4 marks a question · 37% with a figure or table · 43% with code · biggest 18 marks
Assessment objectives — how it is examined
Every part of every current-syllabus question filed under Cambridge's AO1 / AO2 / AO3 (from its command word and what it asks you to do), so you know whether this topic pays for definitions, for applying, or for judging and building.
- AO1 Knowledge & understanding
- AO2 Apply & analyse
- AO3 Design, program & evaluate
Paper 1 as a whole
| Paper 1 | Syllabus | Measured |
|---|---|---|
| AO1 Knowledge & understanding | 60% | 68% |
| AO2 Apply & analyse | 40% | 32% |
| AO3 Design, program & evaluate | 0% | 0% |
Syllabus = Cambridge's grid; measured = the bank's current-syllabus papers.
Inside the topic — every syllabus bullet, measured
Each part of each question is filed under the bullet it examines; the numbers are per Paper 1 sitting, exactly like the topic's. Open a bullet for its own Statometer.
1.1Data representation#7 of 25 on Paper 1Banker · 7883% next paper4.4 marks28/33 sittings↗ May/Jun 2026Banker · 7883%
4.4 · 26% of topic28/33May/Jun 2026latest series · ↗Asked in nearly every paper — the bullet to know cold.Syllabus: binary prefixes (kibi, mebi, gibi, tebi) vs decimal prefixes; binary, denary, hexadecimal, BCD, one's and two's complement; converting between them
- Next Paper 1
- 83%
- 8 in 10
- Marks a paper
- 4.4
- 6% of the paper · 26% of the topic
- Asked in
- 28 / 33
- Paper 1 sittings · 58 questions
- Last asked
- May/Jun 2026
- 9618/13 · Q6 · 6 marks · 11-series streak
- Asked in 28 of 33 Paper 1 sittings — about 8 papers in 10.
- About 4.4 marks a paper (6% of Paper 1; 26% of the topic's marks across its 4 bullets).
- Last asked May/Jun 2026 · 9618/13 · Q6 (6 marks) — in the most recent series.
- Asked in each of the last 11 series.
- Rising: 4 → 4.8 marks a paper.
- Usually “Convert” or “Show”.
- Biggest chunk of marks so far: 8 in May/Jun 2026 · 9618/11 · Q1.
- It is examined mostly as AO2 (Apply & analyse, 74%), the rest AO1 (26%) — you must apply it to the given data or scenario — work it out, trace it, explain it in context.
Last 12 sittings↗ RisingAssessment objectives
AO1 26%AO2 74%- AO1 Knowledge & understanding
- AO2 Apply & analyse
- AO3 Design, program & evaluate
- Convert69%
- Show50%
- Complete35%
- State35%
1.1Binary arithmetic#16 of 25 on Paper 1Regular · 4764% next paper2.1 marks20/33 sittings→ May/Jun 2026Regular · 4764%
2.1 · 10% of topic20/33May/Jun 2026latest series · →Set most sessions for a few marks; know the definition and one example.Syllabus: addition and subtraction with positive and negative integers; overflow; where BCD and hexadecimal are used; ASCII, extended ASCII and Unicode
- Next Paper 1
- 64%
- 6 in 10
- Marks a paper
- 2.1
- 3% of the paper · 10% of the topic
- Asked in
- 20 / 33
- Paper 1 sittings · 29 questions
- Last asked
- May/Jun 2026
- 9618/13 · Q6 · 2 marks · 5-series streak
- Asked in 20 of 33 Paper 1 sittings — about 6 papers in 10.
- About 2.1 marks a paper (3% of Paper 1; 10% of the topic's marks across its 4 bullets).
- Last asked May/Jun 2026 · 9618/13 · Q6 (2 marks) — in the most recent series.
- Asked in each of the last 5 series.
- Usually “Show” or “Convert”.
- Biggest chunk of marks so far: 6 in May/Jun 2021 · 9618/12 · Q6.
- It is examined mostly as AO1 (Knowledge & understanding, 51%), the rest AO2 (49%) — definitions and descriptions in syllabus words score.
Last 12 sittings→ SteadyAssessment objectives
AO1 51%AO2 49%- AO1 Knowledge & understanding
- AO2 Apply & analyse
- AO3 Design, program & evaluate
- Show66%
- Convert62%
- Complete52%
- State48%
1.2Multimedia#3 of 25 on Paper 1Banker · 9286% next paper6.8 marks29/33 sittings→ May/Jun 2026Banker · 9286%
6.8 · 50% of topic29/33May/Jun 2026latest series · →Asked in nearly every paper — the bullet to know cold.Syllabus: bitmaps (pixel, file header, resolution, colour depth) and file-size estimates; vector graphics (drawing objects, properties, drawing list); sound sampling rate and resolution
- Next Paper 1
- 86%
- 9 in 10
- Marks a paper
- 6.8
- 9% of the paper · 50% of the topic
- Asked in
- 29 / 33
- Paper 1 sittings · 77 questions
- Last asked
- May/Jun 2026
- 9618/13 · Q8 · 6 marks · 11-series streak
- Asked in 29 of 33 Paper 1 sittings — nearly every paper.
- About 6.8 marks a paper (9% of Paper 1; 50% of the topic's marks across its 4 bullets).
- Last asked May/Jun 2026 · 9618/13 · Q8 (6 marks) — in the most recent series.
- Asked in each of the last 11 series.
- Usually “Describe” or “Explain”: full sentences with a reason, not one-word answers.
- Biggest chunk of marks so far: 12 in Oct/Nov 2021 · 9618/12 · Q5.
- It is examined mostly as AO1 (Knowledge & understanding, 74%), the rest AO2 (26%) — definitions and descriptions in syllabus words score.
Last 12 sittings→ SteadyAssessment objectives
AO1 74%AO2 26%- AO1 Knowledge & understanding
- AO2 Apply & analyse
- AO3 Design, program & evaluate
- Describe61%
- Explain60%
- Show39%
- Give39%
1.3Compression#17 of 25 on Paper 1Regular · 4764% next paper2 marks23/33 sittings↘ May/Jun 2026Regular · 4764%
2 · 15% of topic23/33May/Jun 2026latest series · ↘Set most sessions for a few marks; know the definition and one example.Syllabus: the need for compression; lossy vs lossless and when to use each; compressing text, bitmaps, vector graphics and sound, including run-length encoding
- Next Paper 1
- 64%
- 6 in 10
- Marks a paper
- 2
- 3% of the paper · 15% of the topic
- Asked in
- 23 / 33
- Paper 1 sittings · 45 questions
- Last asked
- May/Jun 2026
- 9618/13 · Q3 · 2 marks · 11-series streak
- Asked in 23 of 33 Paper 1 sittings — about 7 papers in 10.
- About 2 marks a paper (3% of Paper 1; 15% of the topic's marks across its 4 bullets).
- Last asked May/Jun 2026 · 9618/13 · Q3 (2 marks) — in the most recent series.
- Asked in each of the last 11 series.
- Easing: 2.4 → 2 marks a paper.
- Usually “Explain” or “Describe”: full sentences with a reason, not one-word answers.
- Biggest chunk of marks so far: 7 in May/Jun 2025 · 9618/11 · Q2.
- It is examined almost entirely as AO1 (Knowledge & understanding, 82%) — definitions and descriptions in syllabus words score.
Last 12 sittings↘ EasingAssessment objectives
AO1 82%AO2 19%- AO1 Knowledge & understanding
- AO2 Apply & analyse
- AO3 Design, program & evaluate
- Explain73%
- Describe64%
- Identify40%
- Show38%
23% of the topic's marks sit in question parts that belong to another topic (scenario questions cross sections) or that no bullet claims; they count for the topic, not for a bullet.
Marks a paper, year by year
Grey years are the previous syllabus (2015–2021, 67 questions) — history, not counted in the rates.
By exam series
- May/Jun18/18 · 19.9 mk
- Oct/Nov15/15 · 21.4 mk
What you need to know4syllabus §1.1, §1.2, §1.3
- 1.1Data representation — binary prefixes (kibi, mebi, gibi, tebi) vs decimal prefixes; binary, denary, hexadecimal, BCD, one's and two's complement; converting between them
- 1.1Binary arithmetic — addition and subtraction with positive and negative integers; overflow; where BCD and hexadecimal are used; ASCII, extended ASCII and Unicode
- 1.2Multimedia — bitmaps (pixel, file header, resolution, colour depth) and file-size estimates; vector graphics (drawing objects, properties, drawing list); sound sampling rate and resolution
- 1.3Compression — the need for compression; lossy vs lossless and when to use each; compressing text, bitmaps, vector graphics and sound, including run-length encoding
Video lectures26ZAK's YouTube channel · play here
AS2023235 views
AS2023711 views
O LevelAS2023425 views
AS2023254 views
O LevelAS20231.1K views
O LevelAS2023626 views
Infographics5draw these the way the examiner expects · download as PNG
Number system conversions
File size calculations
Two's complement, overflow & shifts
Bitmap, vector & sound
Lossless vs lossy compression
Key terms8use these exact words in the exam
Dotted terms are defined in the glossary.
Code help2referenced to the Cambridge pseudocode guide
DECLARE N, V, i : INTEGERDECLARE Bits : STRINGN ← -5V ← 256 + N // 8-bit two's complement valueBits ← ""FOR i ← 1 TO 8Bits ← NUM_TO_STR(V MOD 2) & BitsV ← V DIV 2NEXT iOUTPUT N, " = ", Bits
DECLARE S, Out, Ch : STRINGDECLARE i, Run : INTEGERS ← "AAAABBBCCD"Out ← ""i ← 1WHILE i <= LENGTH(S)Ch ← MID(S, i, 1)Run ← 0WHILE i <= LENGTH(S) AND MID(S, i, 1) = ChRun ← Run + 1i ← i + 1ENDWHILEOut ← Out & NUM_TO_STR(Run) & ChENDWHILEOUTPUT Out
Playground examples5runnable programs for this topic
- Run
Denary → binary by repeated division
MOD 2 gives each bit, DIV 2 moves on; the remainders are read bottom-up.
- Run
Binary → denary with place values
Walk the bits from the right, doubling the place value each time.
- Run
Denary → hexadecimal
Same idea as binary but MOD 16, with a lookup string for the digits A–F.
- Run
Two's complement — negate an 8-bit number
Invert every bit, then add 1 with a carry that ripples from the right.
- Run
Run-length encoding (lossless compression)
Replace runs of the same character with a count and the character.
Assembler4programs to step through the CPU simulator
- Run
Negative results and two's complement
5 − 12 = −7. Look at the binary view of ACC: 11111001 is −7 in 8-bit two's complement.
- Run
Overflow — when the result no longer fits
In an 8-bit accumulator 200 + 100 = 300 cannot be represented. The simulator keeps the value but raises the overflow flag, exactly what the exam wants you to explain.
- Run
LSL / LSR — multiply and divide by powers of 2
Shifting left 1 doubles, right 1 halves (integer). 6 ≪ 2 = 24, 24 ≫ 3 = 3.
- Run
Lower-case to upper-case with SUB #32
ASCII 'a' is 97 and 'A' is 65 — the difference is 32, so subtract it (or AND with B11011111).
Test yourself
Ready to check you know it?
Every round is a fresh random draw, weak cards come back until you get them right, and past-paper questions come with their mark schemes. Marks earn XP on your dashboard.
NewCS Games · 16 to play
Revise this topic by playing
Quiz battles, a daily CS word, SQL whodunnits, logic-gate puzzles and arcade — every game drills the syllabus. Solo against AskZ bots, with friends, or with your whole class. Free, no sign-up.
