Computer Science Comics

Pick a topic and work through its comics in order. Open a comic, then press Next to reveal it one part at a time.

Systems Architecture

From human computers to the CPU: how a computer follows a program, and what makes it faster.

  1. It All Started With People! Before machines, a computer was a person who followed instructions and worked out calculations by hand. 12 parts to reveal
  2. Machine Computers Early machines followed instructions from tape or from their cables, which made changing what they did slow and hard. 12 parts to reveal
  3. Stored Program Computer Design Von Neumann’s design: memory holds both instructions and information, and the CPU fetches and carries out the instructions. 16 parts to reveal
  4. What is a Program? A program is a set of instructions for a particular task, traced step by step through a tiny program stored in memory. 19 parts to reveal
  5. How the CPU Follows a Program The CPU fetches, decodes and executes one instruction at a time, then repeats: the fetch-decode-execute cycle. 14 parts to reveal
  6. Inside the Central Processing Unit (CPU) What the CPU needs to be able to do, and the parts that do each job: the control unit, the ALU and the registers. 18 parts to reveal
  7. CPU Registers Why the CPU needs to hold things for a moment, what it holds, and the very small, very fast storage areas that do it. 12 parts to reveal
  8. CPU Registers – Different Jobs The job of each register (PC, MAR, MDR and accumulator), each with an example value from our little program. 13 parts to reveal
  9. The CPU Has a Problem!! Memory is slower than the CPU, so the CPU has to wait. Cache keeps copies of what it needs soon, close by. 15 parts to reveal
  10. The CPU's Clock! A clock inside the CPU ticks regularly; the number of ticks each second is its clock speed, and higher means faster. 8 parts to reveal
  11. One CPU – Many Mini Workers A core is like a mini CPU. One core does one job at a time; multiple cores can work on different jobs at once. 14 parts to reveal
  12. Getting the CPU to Do More CPU performance and three ways to improve it: a higher clock speed, more cores and a larger cache, each with its effect. 12 parts to reveal

System Software

The operating system: where it came from and the jobs it does for users and programs.

  1. From Human Operators to Operating Systems How software gradually took over the human operator’s jobs, until it became known as the operating system. 23 parts to reveal, then a quick quiz
  2. The OS Makes Computers Easy to Use Why everyday users need an operating system, and five things it does for them: interface, login, apps, files and settings. 12 parts to reveal
  3. What Happens When You Start an App? The OS finds the app in storage and loads it into RAM, the CPU runs it, and several apps take turns on the CPU. 11 parts to reveal
  4. The OS Keeps an Eye on RAM How the OS tracks what is in RAM, frees space when apps close, and uses virtual memory when RAM fills up. 12 parts to reveal
  5. The OS Organises Your Files How the OS keeps files and folders organised, and controls who can access them on a shared computer. 13 parts to reveal
  6. How the OS Makes Programming Easier How the OS and device drivers handle the hardware, so programmers can focus on what their program should do. 17 parts to reveal
  7. The Operating Systems We Use Today Windows, macOS, Linux, Android, iOS and iPadOS: different names, but the same main purpose. 8 parts to reveal