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AS · Practice questions · Utility software and program libraries

Maintain and reuse.

Six original Cambridge-style questions on utility software and program libraries, including DLLs, with mark-scheme solutions.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Problem, then utility.

01
Explain
[2 marks]

Explain why a disk formatter is needed.

  • A new storage device must be prepared before the OS can store files: the formatter sets up the file system / directory structure (tracks and sectors). ✓
  • It can also be used to erase a disk for reuse, partition it, or check it for bad sectors. ✓
02
Explain
[3 marks]

Describe how defragmentation software can improve the performance of a computer with a magnetic hard disk.

  • As files are saved and deleted, files become split into blocks scattered over the disk (fragmented). ✓
  • The defragmenter moves the blocks so each file is stored in contiguous blocks, and groups free space together. ✓
  • The read/write heads move less to read a file, so files are opened faster. ✓
03
Recall
[3 marks]

Identify three utility programs provided with an operating system, other than defragmentation software, and state the purpose of each.

  • Virus checker: detects and removes / quarantines malware. ✓
  • Back-up software: copies data so it can be restored if lost or corrupted. ✓
  • File compression: reduces file size to save storage and transmission time. (Also accept disk formatter, disk contents analysis / repair, with purpose.) ✓
04
Explain
[3 marks]

Software under development is often constructed using code from program libraries. Explain three benefits of this to the developer.

  • Saves time: the routines do not have to be written from scratch. ✓
  • The routines are already tested, so they are more reliable and reduce testing time. ✓
  • Complex routines written by experts can be used without the developer needing that expertise (and give consistency across programs). ✓
05
Explain
[4 marks]

Explain the benefits of using Dynamic Link Library (DLL) files.

  • The DLL is linked at run time, so its code is not included in the executable file, making the executable smaller. ✓
  • One copy of the DLL in memory can be shared by several programs running at the same time, saving memory. ✓
  • The DLL can be updated or fixed by replacing one file, without recompiling the programs that use it. ✓
  • Saves development time as the routines are pre-written and pre-tested. ✓
06
Analysis
[2 marks]

A company updates a DLL used by several of its programs. One program stops working after the update. Explain why this could happen.

  • The program is linked to the DLL at run time, so it now uses the new version. ✓
  • The new version may have changed a routine's name, parameters or behaviour, so it is no longer compatible with the program. ✓

Mark this once you have attempted all six and checked your working. It records a Practiced badge on the topic and adds a one-time bonus. Revealing the solutions alone does not count.