System Software and the Operating System

Overview

Recall questions on the four types of system software, the need for an operating system, its main functions and the role of utility programs.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Name the four types of system software.

   Model answer

   Operating systems, utility programs, libraries, and translators (assemblers, compilers and interpreters).

2. 2

   Understand the need for an operating system: what would using a computer be like without one?

   Model answer

   Every program would have to contain its own code to drive the disk, keyboard, screen and network, to lay out the file system, to allocate memory and to decide when it could use the processor. Only one program could safely run at a time, programs could freely overwrite each other's memory, and software would have to be rewritten for every different combination of hardware. The operating system is needed so that this work is done once, centrally and safely, for every program.

3. 3

   State the main functions of an operating system.

   Model answer

   Managing the processor and scheduling processes; managing main memory and allocating it to processes; managing files and directories on secondary storage; managing input and output devices through drivers and buffers; handling interrupts; providing a user interface (graphical or command line); providing security through user accounts, passwords and access rights; and loading and running application programs.

4. 4

   Understand the need for utility programs: what are they for?

   Model answer

   Utility programs are needed to maintain, optimise, protect and repair the computer system: housekeeping jobs that the operating system does not do as part of ordinary running, but that keep the machine healthy and its data safe.

5. 5

   Describe the function of four utility programs.

   Model answer

   A disk defragmenter rearranges the parts of files on a magnetic disk so each file occupies contiguous sectors, reducing head movement and speeding access. A backup utility copies data to another medium on a schedule so it can be recovered after loss or corruption. Antivirus software scans files and memory for known malware signatures and suspicious behaviour, and quarantines or removes what it finds. A compression utility encodes files so they occupy fewer bytes for storage or transmission, and restores them afterwards. Others include disk formatting, file management, encryption, firewalls and system monitoring or clean-up tools.

6. 6

   Why is defragmentation of little value on a solid-state drive?

   Model answer

   Defragmentation exists to reduce the physical movement of read/write heads across a spinning platter. A solid-state drive has no moving parts and takes essentially the same time to reach any block, so rearranging files gains almost nothing. Worse, the rewriting involved consumes some of the drive's finite number of write cycles.

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