Bytesize CS

Computer Science revision in bytesize pieces

Topic slides, videos, exam questions and interactive models for OCR Computer Science. Choose your course to get started.

OCR J277

GCSE

  • Paper 1: Computer systems
  • Paper 2: Computational thinking, algorithms and programming
  • Past papers and mark schemes
Go to GCSE revision →
Coming soon

A level

Revision for OCR A level Computer Science (H446) is on its way.

Bytesize CodeLearn Python one bite at a time: short lessons, instant feedback, XP and streaks, with OCR Exam Reference Language for the exam.

Start coding →

Practice tools

Binary to denary4-bit, 8-bit and two’s complement Denary to binaryClick the bits to build the number Binary additionNibbles and bytes, with carries and overflow Binary shiftsLogical shifts left and right, 1 to 5 places HexadecimalHex, binary and denary, with a step via binary FDE cycle explorerFollow addresses and instructions through the CPU 🃏 Pioneer cardsGet a streak of 10 in a tool to collect computing pioneers

A level practice tools

Floating pointNormalised mantissa and exponent, to and from denary Binary subtractionSubtract by adding the two’s complement Bit maskingAND, OR and XOR masks to set, clear, flip and keep bits Boolean algebraDe Morgan’s and the other laws: use, name and simplify