Fundamentals of Computer Organisation and Architecture

What Fundamentals of Computer Organisation and Architecture covers

The stored program concept, the processor and its registers, the Fetch-Execute cycle, instruction sets and addressing modes, interrupts, performance factors, and input, output and storage devices. Examined on Paper 2.

The 11 subtopics

Each one has its own page.

• Internal components, buses and von Neumann and Harvard architecturesRecall questions on the processor, main memory and I/O controllers, the address, data and control buses, addressable memory, and the von Neumann and Harvard architectures and the von Neumann bottleneck.Open →
• The Stored Program Concept and the ProcessorRecall questions on what makes a machine a stored-program computer, why the idea mattered, and the components of the processor.Open →
• The Fetch-Execute cycleRecall questions on the fetch, decode and execute stages, the register used at each step, register transfer notation, and what changes when a branch is taken.Open →
• The processor instruction setRecall questions on opcode and operand, why an instruction set is processor specific, and decoding a given byte into its operation and its operand.Open →
• Addressing modesRecall questions on immediate against direct addressing, what ADD 20 does under each, their relative speed and flexibility, and why a loop counter needs direct addressing.Open →
• Machine-Code OperationsRecall questions on the instruction set at this level and on the load, store, add and subtract instructions.Open →
• Shifts, Halting and Assembly Language ProgramsRecall questions on logical shifts left and right and their arithmetic effect, the halt instruction, hand-tracing assembly language programs with loops and branches, and why labels are used.Open →
• InterruptsRecall questions on what generates an interrupt, the service routine, the effect on the Fetch-Execute cycle, and why the volatile environment is saved on a stack.Open →
• Factors affecting processor performanceRecall questions on cores, cache, clock speed, word length and bus widths, and on why each of them stops delivering gains at some point.Open →
• Input and output devicesRecall questions on barcode readers, digital cameras, laser printers and RFID, how each works, and the situations each is and is not suited to.Open →
• Secondary storage devicesRecall questions on hard disks, optical disks and solid-state drives, how each stores data, what makes up access time, and which suits a given job.Open →

What you need to know

Answer each one before you reveal it.

Take Fundamentals of Computer Organisation and Architecture further

The same content, four other ways.

Commonly confused

Pairs that lose marks when they are blurred together.

• Von Neumann architecture vs Harvard architecture

  Von Neumann architecture: instructions and data share one memory and bus system. Harvard architecture: instructions and data use separate memories and buses.

• Immediate addressing vs Direct addressing

  Immediate addressing: the operand field contains the actual value. Direct addressing: the operand field contains the memory address of the value.

• Hard disk drive vs Solid-state drive

  Hard disk drive: magnetic storage using spinning platters and moving heads. Solid-state drive: electronic storage using flash memory without moving parts.

Questions from this topic

Each one with the model answer underneath.

1. 1

   Name the basic internal components of a computer system.

   Model answer

   The processor, main memory, the address bus, the data bus, the control bus, and the input/output controllers that connect peripherals to the system. All of these are mounted on or attached to the motherboard, and the buses are the wires that carry signals between the rest.

2. 2

   What is the role of the processor?

   Model answer

   The processor is the component that actually runs programs. It repeatedly fetches machine code instructions from main memory, decodes them and executes them, performing arithmetic and logical operations on data and generating the control signals that direct every other component. Everything else in the machine exists to supply it with instructions and data or to accept its results.

3. 3

   What is the role of main memory, and how does it relate to the processor?

   Model answer

   Main memory holds the machine code instructions and the data of the programs currently running, in numbered locations that the processor can reach directly and quickly. The processor cannot execute a program from secondary storage: the program must first be loaded into main memory. The processor supplies an address on the address bus and the instruction or datum travels back along the data bus. Main memory is volatile, so its contents are lost when power is removed.

4. 4

   Understand the need for communication between components: why is a bus needed?

   Model answer

   The processor, memory and input/output controllers are physically separate, so signals have to travel between them. Wiring every component individually to every other would need an unmanageable number of connections and could not be extended. A bus solves this by providing one shared set of parallel lines that every component connects to, so any component can send to any other over the same wires, and a new device can be added simply by attaching it to the bus.

5. 5

   What is a bus?

   Model answer

   A bus is a set of parallel wires, or lines, that carries signals between the components of a computer. The number of lines is the width of the bus, and each line carries one bit at a time, so all the bits of an address or a data word travel simultaneously. Only one transfer may take place on a bus at any moment, so access to it has to be controlled.

6. 6

   Describe the address bus and what its width determines.

   Model answer

   The address bus carries the address of the memory location or input/output port that the processor wants to read from or write to. It is unidirectional: addresses travel out of the processor only. Its width determines how many different locations can be distinguished, because n lines give 2 to the power n distinct addresses. A 16-line address bus can therefore address 65,536 locations, and adding one line doubles the addressable memory.

What is inside Levo

Six ways to work the same material.

Fundamentals of Computer Organisation and Architecture revision questions

What does Fundamentals of Computer Organisation and Architecture cover in AQA A-Level Computer Science?

11 subtopics: internal components, buses and von neumann and harvard architectures, the stored program concept and the processor, the fetch-execute cycle, the processor instruction set, addressing modes, machine-code operations, shifts, halting and assembly language programs, interrupts, factors affecting processor performance, input and output devices and secondary storage devices. Each one has its own page with questions and model answers.

How is Fundamentals of Computer Organisation and Architecture organised?

By the AQA 7517 specification, subtopic by subtopic, so it matches the order you are taught it in.