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Operating Systems and File Management

Computer Studies · WAEC and JAMB · SS2 and SS3

The operating system is the program that makes every other program possible, and the examiner wants its functions and its types, not a list of Windows versions. File management is the practical half, and it is tested through paths, extensions and operations.

What you need to know

  • An operating system is the system software that manages all the hardware and software resources of a computer and provides the interface between the user and the machine. Without it the hardware cannot be used, which is why it is loaded first.
  • Its functions, which should be learnt as a list: memory management, allocating and reclaiming RAM for each program; process or job management, deciding which task gets the processor and for how long; file management, creating, naming, storing, retrieving and deleting files; device management through drivers; input and output control; security and access control through user accounts and passwords; error detection and reporting; resource allocation among competing users; and providing the user interface.
  • By interface, operating systems are command line or graphical. A command line interface requires the user to type exact commands and so is fast and light but hard for beginners; MS-DOS and the Linux shell are examples, with commands such as DIR to list files, CD to change directory, MD to make a directory, COPY, REN, DEL, CLS and FORMAT. A graphical user interface uses windows, icons, menus and a pointer, so it is easy to learn but demands much more memory and processing power.
  • By the number of users and tasks: a single-user single-tasking system runs one program for one user, as MS-DOS did; a single-user multitasking system lets one user run several programs at once, as Windows and macOS do; a multi-user system serves many users at the same time on one machine, as UNIX and Linux servers do; a multiprocessing system uses more than one processor.
  • By mode of operation: a batch system collects jobs and processes them together without user interaction, which suits payroll and utility billing; a time-sharing system gives each user a small slice of processor time in rotation so that everyone appears to be served at once; a real-time system must respond within a strict time limit, as in air traffic control, missile guidance and hospital monitors; a distributed system spreads processing across several linked computers.
  • Named examples to quote: Microsoft Windows in its successive versions, macOS, Linux distributions such as Ubuntu and Fedora, UNIX, Android and iOS for mobile devices, and Chrome OS.
  • Booting is the process of starting a computer and loading the operating system into RAM. A cold boot is starting from a completely switched-off state; a warm boot is restarting a machine already on, traditionally with Ctrl, Alt and Delete.
  • When power comes on, firmware in ROM, the BIOS or UEFI, runs the Power-On Self-Test to check that the memory, keyboard, display and drives are present and working. The bootstrap loader then finds the operating system on the disk and copies it into RAM, and control passes to it.
  • A file is a collection of related records or data stored under one name on a storage medium. A folder, also called a directory, is a named container that holds files and other folders so that storage is organised rather than heaped together.
  • A path states exactly where a file lives, beginning at the drive and listing each folder in order, for example C:\Users\Student\Documents\CivicNote.docx. The topmost level of a drive is the root directory, and a folder inside another folder is a subfolder.
  • The file operations you should be able to name and describe are create, open, save and save as, rename, copy, move or cut and paste, delete and restore from the Recycle Bin, search, sort, compress or zip, set attributes such as read-only or hidden, print, share and back up.
  • The extension after the dot tells the system which program opens the file. Learn these: .docx for Word, .xlsx for Excel, .pptx for PowerPoint, .accdb for Access, .pdf for a portable document, .txt for plain text, .jpg and .png for images, .mp3 for audio, .mp4 for video, .exe for an executable program, .zip and .rar for compressed archives, .html for a web page, and .py, .c and .java for program source files.
  • Records inside a file can be organised serially, in no particular order; sequentially, in order of a key field; index-sequentially, with an index that allows both direct and sequential access; or randomly, where a calculation on the key gives the address directly. Access is correspondingly sequential or direct.
  • Good practice is examinable and practical: give files meaningful names rather than New Document 1, keep a logical folder structure by subject and term, save frequently with Ctrl and S, back up to an external drive and to cloud storage such as Google Drive or OneDrive, scan every flash drive before opening it, and remember that Shift with Delete bypasses the Recycle Bin and the file is gone. Useful shortcuts are Ctrl C to copy, Ctrl X to cut, Ctrl V to paste, Ctrl Z to undo, Ctrl A to select all, Ctrl F to find, Ctrl P to print and F2 to rename.

Key terms

Operating system
System software that manages the hardware and software resources of a computer and provides an interface between the user and the machine.
Multitasking
The ability of an operating system to keep more than one program running at the same time by sharing processor time among them.
Real-time system
An operating system that must process input and respond within a strictly defined time limit, as required in air traffic control or medical monitoring.
Booting
The process of starting a computer and loading the operating system from secondary storage into main memory.
File
A collection of related data or records stored on a storage medium under a single name.
Directory
A named container, also called a folder, used to group files and other directories so that storage is organised.
File extension
The suffix after the dot in a file name that identifies the file type and the program that opens it.

Worked examples

State six functions of an operating system. (12 marks)

  1. Think of the resources the system has to share out: memory, the processor, files, devices, and access itself.
  2. Turn each resource into a management function and add the user interface as the sixth.
  3. Write six distinct functions. Memory management and allocation of RAM are the same point and will earn only one mark.

Given the path C:\SS3\ComputerStudies\Assignments\project.docx, identify the drive, the root directory, the subfolders, the file name and the file type. (5 marks)

  1. Read the path from left to right; each backslash separates one level from the next.
  2. The letter with the colon is the drive, and the backslash immediately after it is the root.
  3. The last item is the file, and the part after its dot is the extension that gives the file type.

The mistake to avoid

Candidates answer a question on the functions of an operating system by listing examples of operating systems. Windows and Linux are examples, not functions. The second common slip is describing booting as switching on the power; booting is the loading of the operating system into memory, which follows the power-on self-test. Candidates also confuse Delete, which sends a file to the Recycle Bin where it can be restored, with Shift and Delete, which removes it permanently.

In the exam

Learn the functions as a numbered list of six to eight and reproduce them in order, because this is the single most repeated theory question in the chapter. When a question gives a path, label each component separately rather than describing it in prose. Quote file extensions exactly, with the dot and in lower case.