The disk is nearly full
Your laptop is slow. The disk is nearly full. You want to email a big folder, but it is too big to send. You also think you might have a virus.
What can you do? You use small helper programs. They are called utilities. They look after the computer, so that other programs can do their work.
Key words
| Word | What it means | Example |
|---|---|---|
| Utility | A small program that looks after the computer. | A backup tool |
| File management | Making, naming, moving, copying and deleting files and folders. | File Explorer |
| Fragmented | Split into pieces that are far apart on a disk. | A file in 50 pieces |
| Defragmenter | A utility that joins the pieces of each file together again. | Defragment and Optimise Drives |
| Lossless | Compression that keeps every bit of the data. | ZIP |
| Lossy | Compression that throws away some detail for ever. | JPEG, MP3 |
| Compression | Making a file smaller so it uses less space. | A ZIP file |
| Package manager | A utility that finds, installs, updates and removes software for you. | The app store on a phone |
| Malware | Bad software made to harm a computer or steal data. | A virus |
| Firewall | A program that blocks unwanted data from reaching the computer. | The Windows firewall |
| Backup | A copy of files kept in another place, in case the first copy is lost. | A copy on a cloud drive |
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File management
A file manager shows your files in folders. You can make a folder, rename a file, move it, copy it, search for it and delete it.
Good habits save time. Give files clear names. Keep a folder for each subject. Do not keep ten copies of one file with names like "final2" and "final3".
Defragmenters
A hard disk saves a file in whatever free space it finds. After many saves and deletes, one file can be in many pieces. We say it is fragmented. The disk must move to many places to read one file, so it is slower.
A defragmenter moves the pieces so each file is in one place. This helps a magnetic hard disk. An SSD has no moving parts, so it does not need it.
Try it: how many pieces?
# Each letter is a block of a file. A dash is free space.
disk = ["A", "-", "B", "A", "-", "B", "A"]
pieces = 0
last = "-"
for block in disk:
if block == "A" and last != "A":
pieces = pieces + 1
last = block
print("File A is in", pieces, "pieces")
# Put the three A blocks next to each other and run it again.
# A defragmenter does that for every file.
File compression
Compression makes a file smaller. A smaller file saves space and is faster to send.
A ZIP file holds one or many files in a smaller space. You open it to get the exact files back. Compression is useful for storage, and for an email attachment that is too big.
Extra: Lossless and lossy
Lossless compression keeps every bit of the data. A ZIP file is lossless, so you get the exact file back.
Lossy compression throws away detail that people hardly notice. A JPEG photo or an MP3 song is lossy. You cannot get the lost detail back.