Computer Hardware, Software and Operating Systems
What the examiner tests
Hardware/software classification, the role of the operating system, and identification of devices and software types in short-answer questions.
Core ideas
- CPU = ALU + CU + registers. Registers are tiny, very fast storage inside the CPU (program counter, instruction register, accumulator). Clock speed in GHz is one measure of speed.
- Primary memory: RAM is volatile and holds the program currently running; ROM is non-volatile and stores firmware/BIOS. Cache is faster and smaller than RAM and sits between CPU and RAM.
- Secondary storage: magnetic (HDD), solid-state (SSD, pen drive, memory card), optical (CD/DVD/Blu-ray). Non-volatile, cheaper per GB, slower.
- Input devices: keyboard, mouse, scanner, microphone, barcode reader, biometric sensor. Output: monitor, printer, speaker, plotter.
- Software is a set of programs. System software runs the machine: operating system, device drivers, utilities, language translators (compiler, interpreter, assembler). Application software does user work: word processor, spreadsheet, browser, custom billing software.
- OS functions: process management, memory management, file management, device management, security, and the user interface. Types: batch, multiprogramming, time-sharing, real-time, distributed. Examples: Windows, Linux, Android, macOS.
Worked example
A shopkeeper buys a laptop with 8 GB RAM, a 512 GB SSD, Windows 11 and Tally. Classify them. RAM and SSD are hardware (primary and secondary memory respectively). Windows 11 is system software. Tally is application software, and it runs only after the OS loads it into RAM.
Traps
- Calling ROM volatile, or saying ROM can never be changed (EEPROM/flash firmware can be updated).
- Saying a hard disk is primary memory.
- Treating Android as application software - it is an operating system.
- Mixing open-source with freeware; they are different ideas.