Computer Fundamentals and Hardware
What the domain covers
Computer Fundamentals and Hardware tests your grasp of what a computer is made of and how its parts cooperate. Expect questions on the von Neumann model, CPU organisation, memory hierarchy, storage devices, input/output, buses, ports, and the units used to measure capacity and speed.
Core rules and concepts
- The CPU contains the arithmetic logic unit (ALU), control unit (CU), and registers. The ALU performs arithmetic and logic; the CU fetches, decodes, and coordinates; registers hold immediate operands and addresses.
- Primary memory is directly addressable by the CPU. RAM is volatile and holds running programs; ROM is non-volatile and holds firmware such as the initial boot instructions.
- Cache is small, fast SRAM between CPU and RAM. The hierarchy is registers → cache → RAM → secondary storage, trading capacity for speed.
- Secondary storage (HDD, SSD, optical, flash) is non-volatile. SSDs have no moving parts and lower access latency than HDDs.
- A bus carries data, addresses, and control signals. The address bus width limits addressable memory; the data bus width affects how much data moves per transfer.
- 1 byte = 8 bits; 1 KiB = 1024 bytes, 1 MiB = 1024 KiB. Clock speed is measured in hertz, not bytes.
Worked example
A byte-addressable CPU has a 32-bit address bus. How much memory can it address? Each address selects one byte, so the number of addresses is 2^32. That equals 4,294,967,296 bytes = 4 GiB. If the bus were 20 bits, the limit would be 2^20 bytes = 1 MiB. Reason: address lines choose locations; data lines determine word size, not the count of locations.
Traps that cost marks
Do not confuse bit and byte, or GiB with GB. RAM is not a permanent store. ROM is not the same as a hard disk. A faster clock does not automatically mean faster overall performance, because cache, cores, and storage also matter. Read address bus versus data bus carefully.