A utility program is system software that looks after the computer: protecting it, tidying it or helping the user manage data. In the exam you are given a problem and asked to name the utility that solves it, or given a utility and asked what it does.
This lesson builds on the sorting idea in operating system and application roles.
What are the common utilities and what do they do?
| Utility | What it does | A problem it solves |
|---|---|---|
| Antivirus | Scans files and programs for malware, and removes or quarantines it | A downloaded file may be infected |
| Backup | Copies data to another location so it can be restored | A drive fails or a file is deleted by accident |
| Disk defragmentation | Rearranges the scattered pieces of files on a magnetic hard disk drive so each file is stored together | The disk is slow because files are split into pieces |
| Disk formatting | Prepares a disk for use by setting up its structure for storing files | A new drive cannot yet store files |
| Compression | Reduces file size by re-encoding the data | A file is too large to email |
| File manager | Lets the user view, copy, move, rename and delete files | The user needs to organise folders |
| Disk repair | Checks the disk for errors and tries to fix them | Files will not open because of disk errors |
Worked example
A student has a folder of 240 MB of photographs to send by email. The email service allows 200 MB. Which utility helps, and by how much must the size reduce?
Step 1. The problem is that the file is too large. That points to compression.
Step 2. The folder is 240 MB and the limit is 200 MB. The size must fall by at least 240 − 200 = 40 MB.
Step 3. Suppose the compressed folder is 150 MB. The saving is 240 − 150 = 90 MB. As a fraction of the original: 90 ÷ 240 = 0.375, so the size is reduced by 37.5%.
Step 4. Check: 37.5% of 240 = 0.375 × 240 = 90 MB, which matches. 150 MB is below 200 MB, so the folder can be sent.
Step 5. The student also wants to be safe if the laptop breaks. Compression does not do that, since it is still only one copy. The utility for that problem is backup.
The mistake to watch for
Mistaken answer: “Defragmentation deletes unwanted files to free up space.”
That describes a clean-up tool, not defragmentation. Defragmentation moves the pieces of existing files so that each file sits together. No data is deleted and no space is created.
A related slip is using “formatting” for something that tidies files. Formatting prepares a disk and normally erases what was on it.
When you describe a utility, use the pattern what it does, then the benefit. For defragmentation: it rearranges the pieces of files so each is stored together, so the disk can read them faster.
Check yourself
1. A laptop with a magnetic hard disk drive has become slow at opening large files. Which utility might help and why?
Show answer
Disk defragmentation. It rearranges the split pieces of each file so they are stored together, so the read head moves less and files open faster.
2. A school wants to be able to recover coursework if a computer is stolen. Which utility, and what does it do?
Show answer
Backup. It copies the data to another location, such as an external drive or online storage, so it can be restored on a new computer.
3. A 60 MB file is compressed to 45 MB. Calculate the percentage reduction.
Show answer
Saving = 60 − 45 = 15 MB. 15 ÷ 60 = 0.25. The reduction is 25%. Check: 25% of 60 = 15.
Where this leads next
The final lesson in this module applies everything to a device with a fixed job, in discuss an embedded system with its constraints. To rehearse the vocabulary, use the software and systems practice set.
If tool names and descriptions still run together, our teachers can drill them with fresh scenarios in online one-to-one Computer Science tuition.