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بِسْمِ اللَّهِ الرَّحْمَٰنِ الرَّحِيمِ

Free forever · 2210 · 0478 · 9618

Stop revising.
Start running it.

Cambridge O Level, IGCSE and A Level Computer Science (2210 · 0478 · 9618) — the only CS site where pseudocode, Python, SQL, assembly and Prolog actually run, every topic has its notes and an assignment with solutions, the past papers are already sorted, the quizzes mark themselves and the tutor answers at 2 a.m. Built by ZAK, the teacher behind 25+ years of A*s in Karachi.

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cswithzak.com — the tour

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AI-narrated video overview of this pageYouTube

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grade.pseudo · CAIE 9618
Open full Playground

Press Run — this is a real interpreter, not a picture.

“Don't let yesterday take up too much of today.” — Will Rogers ✦“If you think your teacher is tough, wait till you get a boss.” — Bill Gates ✦“Everyone should learn how to program a computer, because it teaches you how to think.” — Steve Jobs ✦“The best way to predict the future is to invent it.” — Alan Kay ✦“I am not a teacher, I am an awakener.” — Zafar Ali Khan ✦“Move fast and break things — then fix them, with a trace table.” — ZAK, probably ✦“Don't let yesterday take up too much of today.” — Will Rogers ✦“If you think your teacher is tough, wait till you get a boss.” — Bill Gates ✦“Everyone should learn how to program a computer, because it teaches you how to think.” — Steve Jobs ✦“The best way to predict the future is to invent it.” — Alan Kay ✦“I am not a teacher, I am an awakener.” — Zafar Ali Khan ✦“Move fast and break things — then fix them, with a trace table.” — ZAK, probably ✦

Pick your level

Every topic. Every paper. Nothing you have to hunt for.

Each topic page bundles AskZ-written Smart Notes, an assignment with solutions, videos, topical past-paper questions with mark schemes, a quiz, a flashcard deck, infographics and runnable pseudocode. Three clicks from here to revising.

2210 · 0478

O Level

Paper 1 theory + Paper 2 problem-solving. Where the habit starts.

10
topics
1,627
real exam Qs
434
quiz Qs
594
flashcards

Open O Level

9618

AS Level

Papers 1 & 2. Theory gets deeper, pseudocode gets real.

12
topics
683
real exam Qs
502
quiz Qs
616
flashcards

Open AS Level

9618

A2 Level

Papers 3 & 4. OOP, recursion, files, the lot.

8
topics
517
real exam Qs
405
quiz Qs
494
flashcards

Open A2 Level

Not just notes

Tools that do the boring part for you.

Five languages that run in your browser — pseudocode, Python, SQL, assembly and Prolog — AskZ-written notes and assignments for every topic, and everything else below. All live on this page; nothing is a screenshot.

World first

ZAK's Pseudocode Playground

The full CAIE 9618 pseudocode standard, running in your browser: records, files, classes, recursion, pointers, exceptions. 111 worked examples (and the same again in Python), a trace table for every run, and errors that point at the exact line. You already ran it in the hero.

Open the Playground

PROCEDURE Swap(BYREF A, B : INTEGER)

DECLARE T : INTEGER

T ← A

A ← B

B ← T

ENDPROCEDURE

$ X=7 Y=3 → X=3 Y=7 ✓

New · written by AskZ

AskZ Smart Notes

Complete notes for all 30 topics, written once by AskZ from ZAK's material, the syllabus, the mark schemes and past papers — with that topic's infographics, quiz, flashcards and real exam questions woven in. Highlight anything to ask about it.

  • Reads like ZAK's notes
  • Saved on your device, works offline
  • Slides download

Open the notes library

New · with solutions

ZAK Assignments

A full assignment for every topic — 3 sets each, 90 in all — built from ZAK's own class assignments and real past papers: figures, model answers, a mark scheme and an examiner's tip on every part. Answer on screen, self-mark for XP, or print the PDF on ZAK's letterhead.

  • Set A
  • Set B
  • Set C
  • PDF

Browse the assignments

Paper 2 & 4

Python Playground

Real Python 3 in your browser, with input(), files, classes and a trace table. 49 examples — the Python twin of every pseudocode topic.

def fact(n):

return 1 if n == 0 else n * fact(n - 1)

 

for i in range(1, 6):

print(i, fact(i))

1 1

2 2

3 6

4 24

5 120

Databases

SQL Lab

43 queries against a ready-made school database — joins, GROUP BY, DDL — with real keys and referential integrity.

SELECT LastName, Title, Mark

FROM STUDENT INNER JOIN ENROLMENT ON …

WHERE Mark >= 95 ORDER BY Mark DESC;

LastNameTitleMark
KhanComputer Science95
IqbalMathematics95
QureshiEnglish96
AS & A2

Assembler & CPU simulator

Every 9618 instruction, stepped through an animated fetch–decode–execute cycle with the exam trace table.

LDD 200; ACC ← [200]

ADD 201; ACC ← ACC + [201]

STO 202; [202] ← ACC

END ; halt

ACC

0

00000000

fetch → decode → execute

A2

Declarative Lab (Prolog)

Facts, rules, queries, backtracking — with the errors an A2 examiner would flag.

parent(sonia, ali).

parent(sonia, ayesha).

mother(M, C) :- parent(M, C), female(M).

?- parent(sonia, X).

X = ali ;

X = ayesha.

Practice

Quizzes that mark themselves

1,341 MCQs with an explanation for every answer. Wrong ones come back until you get them.

Which is a lossless compression method?

  • MP3
  • JPEG
  • RLE
  • H.264

✓ Correct · +10 XP

Paper 2

Flowchart Studio

Draw a flowchart with the Cambridge symbols and run it; type pseudocode and watch the chart draw itself; check your drawing against the mark scheme.

INPUT Mark
↓
Mark ≥ 50?
↓ Yes
OUTPUT "Pass"
↓
Stop
AS & A2

Data structures, live

Stacks, circular queues, linked lists with a free list, binary trees and hash tables — the arrays and pointers the 9618 mark scheme draws.

7
·
·
·

TopPointer = 1

PUSH 7

Paper 1

Networks Lab

Corrupt a bit and let the parity block find it, route packets, cut up an IP address, walk the TLS handshake, break a blockchain.

01011001
10100110
01110000
10001111

sent with even parity…

Auto-marked

Programming tasks, auto-marked

Exam-style scenario tasks marked against hidden boundary and abnormal tests — pseudocode or Python — with a model answer after two attempts.

Paper 2

Trace tables, generated

Paste any algorithm and watch the table fill in. The exact skill Paper 2 tests.

Total ← Total + i · FOR i ← 1 TO 5

iTotalOUTPUT
10
21
33
46
51010
Mark schemes + examiner comments

2,363 real exam questions

Every CS question Cambridge has asked since 2015 (and the still-relevant ones back to 2010), sorted by topic, with the mark scheme — and what the examiner said about it — one tap away.

Never before

The Statometer

Every topic measured against 180 real Cambridge papers: the odds it is set next time, marks a paper, trend, command words, what inside it gets asked — ranked, and re-ordered by your own quiz record. Updates itself with every new session.

Paper 1

Logic gates lab

Type a Boolean expression, get the circuit and the truth table instantly.

X = (A AND NOT B) OR (NOT A AND B)

ABX
000
011
101
110
A2 §15.2

Boolean algebra & K-map lab

Karnaugh maps looped the way Cambridge draws them, every algebra law named, adders and flip-flops live — and Paper 3 practice marked like the mark scheme.

ABCD00011110000111100000101110110000

T = B.D + A.D

Watch

572 video lectures

522 hours of ZAK's YouTube — topic lectures, past-paper walkthroughs, Zakathon marathons — indexed by syllabus topic and playable right here.

Paper 1

Number systems lab

Binary, hex, two's complement and A2 floating point, with the working shown. Practice mode included.

Denary150
Binary10010110
Hex96
10010110
Memorise

Flashcards

1,704 cards across 93 decks. Flip, rate, repeat.

Interrupt
A signal that tells the CPU to pause the current task and run the ISR.

tap to flip · rate · repeat

Complete

Past paper finder

Every 2210, 0478, 9618 and 9608 paper since 2015: QP, MS and examiner reports, filtered by year, session and variant.

Visual

63 exam-ready infographics

One diagram per idea, downloadable as PNG or SVG. Print them, stick them on the wall.

Organise

Exam planner

Your zone's paper dates and Key Times, a live countdown, calendar export and a week-by-week revision plan.

Reference

Pseudocode ↔ Python

Every construct side by side with its Python equivalent. The Paper 2 and Paper 4 cheat sheet.

Reference

Glossary: 39 key terms

Every syllabus term defined in the words that earn the mark, linked to the topic where it is taught.

Exam technique

28 command words, decoded

State, Describe, Explain, Evaluate… what each one wants from you, the mark it loses, and a real question stem for each.

Official

Syllabus + specimen papers

The official 2210, 0478 and 9618 PDFs, pseudocode guides and every specimen paper with its mark scheme — including the 2029 ones.

2,363

real exam questions, by topic

1,341

auto-marked quiz questions

30

topics, each with Smart Notes + assignments

63

exam-ready infographics

271

runnable examples in 5 languages

522

hours of video lectures, by topic

2015→

every past paper since

Zafar Ali Khan (ZAK)

Zafar Ali Khan

O & A Level Computer Science Educator · Entrepreneur · Programmer at Heart · President & Co-founder, ByteCorp · Creator of AskZ

aka ZAK

The person behind the site

“I am not a teacher.
I am an awakener.”

A proud Pakistani educator, entrepreneur and programmer at heart: twenty-five years of O and A Level Computer Science (0478, 2210, 9618) across Karachi's most renowned institutes, thousands of students, A*s and CAIE distinctions every session, and an online following of 65,000+ wherever CAIE CS is offered. ZAK built this free platform because the resources students actually needed did not exist — so he wrote the interpreter, sorted the papers, shot the lectures and trained the tutor himself.

  • The City School
  • Beaconhouse
  • Alpha College
  • Cedar College
  • Whales College
  • Sceptre College
  • Nixor College
  • Foundation Public School
  • Credo
  • Heuser College
  • Reads College
  • DHA Public School
Full story Video lectures WhatsApp ZAK

Watch ZAK teach it

Every lecture, indexed by syllabus topic.

572 videos — 522 hours — from ZAK's YouTube channel, each tagged with the topic it teaches. New uploads land here on their own. These are the latest; press play.

ASPast paper9618 Paper 11 · May/Jun 20252026196 views

ASPast paper9618 Paper 11 · Oct/Nov 20252026180 views

A2Past paper9618 Paper 32 · Oct/Nov 20252026114 views

A2Past paper9618 Paper 31 · Oct/Nov 20252026236 views

All lectures

The ZAK community

65,000+

students and teachers follow ZAK across 8 pages, groups and channels — wherever CAIE Computer Science is offered.

  1. O Level Computer Science

    33K+

  2. A Level Computer Science

    9.6K+

  3. ZAK on YouTube

    8.3K+

  4. O Level CS study group

    7.1K+

  5. Zafar Ali Khan

    6.2K+

  6. @zakonweb

    1.1K

  7. zakonweb

    372

  8. CS with ZAK on Discord

    2
Live · 18 hours ago5 networks · refreshed from each platform daily

Counts are read from each platform once a day — where a network only publishes a rounded figure it is shown with a +. The groups are private, so their member counts are checked by hand. Prefer WhatsApp? Message ZAK directly.

AskZ

Cambridge · Edexcel · AQA · OCR · WJEC Eduqas · CCEA · IB

Every board.
Every subject.
Ask Z.

Revision that knows your syllabus. AskZ began here with Computer Science; at askzbot.com the same tutor covers every subject on seven boards, with the real paper structure and marking that follows the mark scheme.

Start free Find your subject

45 days free. No card.Then Free forever, or pay per subject for the ones you sit.

Sitting Cambridge Computer Science? It is complimentary, in full, right here — start on cswithzak.com.

Free forever

  • Yearly full past papers, free forever
  • Every syllabus point, mapped to papers
  • Topic one of every subject: notes, questions, flashcards
  • The tutor answers every day on the Free plan
01

Pick your syllabus

Choose your board and the exact code you are entered for. Series, syllabus years and the official PDF come with it.

02

Practise with real paper structure

Papers, command words, mark tags like [3] and timings match the exam, so nothing on the day looks new.

03

AskZ marks and explains

Type or photograph an answer. AskZ marks it against the mark scheme and shows the marks you lost and why.

For Students

Pick the subjects you sit this session. They're yours until the last paper.

Find your subject →

For Parents

One Family plan pools subjects across up to four students — every board, one bill.

Family plan →

For Tutors

Your students' syllabus, papers and marking in one place, so lessons start from the mark scheme.

Plans →

For Schools

Campus seats give every student every subject, with the real paper structure for every board you offer.

Campus →

askzbot.com is the AskZ platform for every board and every subject. Computer Science stays free here on cswithzak.com.

Every May

ZAKATHON

Marathon revision workshops right before the CAIE papers. Started as an experiment with a few students in a room, now fills an auditorium every year.

About the endeavour
Karachi · Online

Learn with ZAK in person

Small-group classes for O Level, AS and A2 across 5 centres in Karachi, plus live online sessions for students anywhere.

Centres & registration
Cloud drives

Success Packs

Everything ZAK gives his own students, in one drive. ZAK's notes, tests and mocks plus every CAIE paper, mark scheme and examiner report — one drive per level, updated every session.

What's inside

From the blog

Exam technique, study skills, real talk.

71 posts from ZAK, pulled live from the blog.

Exam techniqueOn this site

The 7 Pseudocode Mistakes That Cost You Marks in Paper 2

Forgetting ENDIF, using ELSE IF, off-by-one FOR loops — the examiner has seen every one of these. Here's the checklist to run before you put your pen down.

6 minRead
Exam techniqueOn this site

How to Read a Mark Scheme Like an Examiner

The mark scheme is the closest thing to the examiner's brain. Learn what 'any two from' really means, why command words matter, and how to stop dropping easy marks.

5 minRead
Video
Study skills

Your Ultimate Guide To Ace Your A-Level Computer Science (9618) with Active Recall

If you're studying A-Level Computer Science (9618), you've likely faced the frustration of reviewing your notes only to feel like you've retained nothing. You're not alone!

3 minRead on Blogger
All posts

Your A* starts with one topic.

Pick a level, open a topic, read the notes, run a bit of pseudocode — or Python, SQL, assembly, Prolog — and try the assignment. That's it. Come back tomorrow and the streak counter does the rest.

Start with a topic WhatsApp ZAK
Enroll nowOnline classes