J277 · two papers · command words · past papers

Exam craft

Paper shapes, command words, and how to use past papers. Optional timing — this site never locks a mock or a score.

Everything on this course is open. Skip, jump, retry. Nothing is locked and there is no required order.

Two written papers. No calculator. No coursework. This page is how the hall works.

Want an automated score today? Sit a multiple-choice mock — Paper 1, Paper 2, optional timer, instant mark. That is a drill, not the real paper. Nothing is locked behind the score.

The two papers

J277/01 Computer systems J277/02 Computational thinking, algorithms and programming
Time 1 hour 30 minutes 1 hour 30 minutes
Marks 80 80
Weight 50% 50%
Calculator No No
Flavour Hardware, data, networks, security, OS, impacts Algorithms, programming, Boolean, languages; Section B long programming

Paper 1 includes multiple choice, short, and extended (especially 1.6). Paper 2 Section A is shorter questions; Section B is the scenario.

AO1 recall, AO2 apply, AO3 create/analyse (Paper 2 carries almost all the AO3). Translation: you cannot only memorise definitions — you have to trace and write.

Rough timing: a mark a minute is a decent compass (90 minutes, 80 marks, some reading). If you want a drill, time one 8-mark discuss, not the whole course.

Command words

Word Do this
State / give / name Short. Often one word or a phrase. No waffle.
Describe What it is / what happens. Full sentences. Usually no “because”.
Explain Because. Link cause → effect. “Clock speed increases so more cycles per second, so more instructions in the same time.”
Compare / difference Both things, explicitly. “X does … whereas Y does …”
Discuss Both sides (or two stakeholders) + conclusion. 1.6 lives here.
Justify Recommendation plus reasons.
Complete Fill the table / algorithm. Do not rewrite the whole question.

Marks in brackets are a hint: (1) is a name; (4) is usually two developed points or four brief ones; (6–8) wants structure.

Show working on binary, file sizes, traces. Wrong final number with a correct method still harvests marks.

Past papers

Official papers and mark schemes live on the Cambridge OCR J277 assessment page.

How to use them without this site turning into a gate:

  1. Pick one question, not a whole paper, the first time
  2. Attempt it closed-book if you want the real feeling — or open-book from these lessons if you are still learning
  3. Mark it yourself against the scheme
  4. Write one sentence: what I will do differently
  5. Come back to the matching unit page and patch the gap

You do not have to finish Paper 1 before Paper 2. You do not have to hit a score before opening merge sort.

When you do sit a full timed paper, use real conditions: 90 minutes, no phone, no calculator, handwriting. Then take the mark scheme and be harsh. That session is yours to start — never a lock on the next unit.


Exercises below are command-word drills and a tiny timed option you control.

Practice · optional · answers on this page

Exercises

Do as many or as few as you like, in any order. Hints and a model answer sit under each task.

command · e1 paper

Same fact, three command words

Topic: cache memory. 1. State what cache is. (1) 2. Describe how cache is used in a CPU. (2) 3. Explain how increasing cache size can improve performance. (2)
Hint
State = name/definition. Describe = what it does. Explain = because / so.
Show a model answer
1. Fast memory on or next to the CPU holding copies of recently used instructions/data. 2. When the CPU needs an instruction or data, it checks cache first; if it is there it is used instead of fetching from slower RAM. 3. A larger cache holds more of the working set, so there are fewer slow RAM accesses, so more time is spent executing rather than waiting.
command · e2 paper

Compare in one sentence pair

Compare a compiler and an interpreter. (4) Write two clear differences, each mentioning both translators.
Hint
“A compiler … whereas an interpreter …”
Show a model answer
A compiler translates the whole source into machine code before it runs, whereas an interpreter translates and runs statement by statement. Compiled programs usually run faster and do not need the compiler at run time, whereas interpreted programs need the interpreter every time and are usually slower.
papers · e3 paper

Which paper?

1. Draw a truth table for A AND NOT B. 2. Explain one ethical issue of CCTV. 3. Complete a trace table. 4. Convert 11010110 to hex. 5. Write a validation loop for a password length.
Hint
01 = systems. 02 = thinking/programming. Some topics only live on one paper.
Show a model answer
1. Paper 2 (2.4) 2. Paper 1 (1.6) 3. Paper 2 (2.1 / Section B) 4. Paper 1 (1.2.4) 5. Paper 2 (2.3 / Section B)
past · e4 think

Optional timed slice (you hold the clock)

If you want pressure: set 12 minutes. Answer one 8-mark 1.6-style discuss from your own head (facial recognition in shops, or energy use of AI). Then stop, even if unfinished, and mark against the 1.6 model structure: stakeholders, both sides, law, limitation, conclusion. If you do not want a timer, skip this. The rest of the course stays open.
Hint
Discuss = both sides + conclusion. Laws if they fit.
Show a model answer
Structure check, not a “right essay”: - Named stakeholders - At least one benefit - At least one harm - A law or licence if relevant (DPA for faces) - A limitation - A one-line conclusion that answers the question

Check yourself · not a gateway

Quiz

Mark it, reveal it, or skip it. A low score does not close anything. Try again as often as you want.

1 papers Each J277 paper is…
2 command “Explain” almost always needs…
3 command A “discuss” answer that only lists benefits will typically…
4 papers Which belong mainly on Paper 2? (Select all that apply)
5 past You must finish every past paper on this site before opening unit 2.1.
6 papers Paper 2 Section B is typically…