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SingaporeComputer Science

Computer Architecture and Operation

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What are the main parts of a CPU, and how do the control unit, ALU and registers work together?

Describe the components of the CPU - control unit, ALU, registers - and the buses connecting it to memory in the von Neumann architecture
A focused answer to the H2 Computing outcome on CPU components. The control unit, arithmetic logic unit and registers, the address, data and control buses, and the stored-program von Neumann architecture.
8 min answer →

How does a processor run a program, one instruction at a time, using the fetch-execute cycle?

Describe the fetch-decode-execute cycle, the registers involved, and how the program counter sequences instructions
A focused answer to the H2 Computing outcome on the fetch-execute cycle. The fetch, decode and execute stages, the program counter, memory address and data registers, the instruction register, and how branching changes the flow.
8 min answer →

How does a CPU respond to events from devices without constantly checking them, and what is an interrupt?

Explain interrupts and interrupt handling, contrast them with polling, and describe how the CPU services and resumes after an interrupt
A focused answer to the H2 Computing outcome on interrupts. What an interrupt is, the interrupt service routine, saving and restoring state, interrupt priorities, and the contrast with polling for input and output.
8 min answer →

How are logical decisions built from gates, and how do we simplify Boolean expressions?

Construct and interpret logic gates and truth tables, write Boolean expressions, and simplify them using Boolean algebra laws
A focused answer to the H2 Computing outcome on digital logic. The AND, OR, NOT, NAND, NOR and XOR gates, building and reading truth tables, writing Boolean expressions, and simplifying them with Boolean algebra laws and De Morgan.
9 min answer →

Why do computers use several kinds of memory, and how does a cache speed things up?

Describe the memory hierarchy from registers to secondary storage, and explain how caching exploits locality of reference
A focused answer to the H2 Computing outcome on the memory hierarchy. Registers, cache, main memory (RAM) and secondary storage, the trade-off between speed, cost and capacity, and how caching uses locality of reference.
8 min answer →