Community resourceWorksheet

J277 1.2.1 Primary storage

Part 1 of 6 · J277 1.2.1-1.2.3 · Memory and storage

The opening worksheet on memory and storage, covering RAM, ROM and where cache fits.

Students will:

  • explain why a computer needs primary storage
  • compare RAM and ROM
  • describe the purpose of each
  • explain the role of cache
  • replace the vague storage answers examiners penalise

Inside: 4 text sections, 3 multiple-choice activities, 2 completion activities, 5 written answers. 18 marks. Suggested teaching time: 40–60 minutes. 1 diagram.

Includes a teacher guide with suggested sections, timings and common misconceptions.

Series: J277 1.2.1-1.2.3 · Memory and storage, part 1 of 6.

Shared by Coding PathwayVerified teacher

  • 14 cells
  • About 45 minutes
  • CC BY-SA 4.0
  • Shared 17 Aug 2026
  • Updated 27 Oct 2026

Preview

The whole resource, exactly as a class sees it. Answers and marking are held back.

Primary storage

The CPU needs quick access to the instructions and data it is using. Primary storage provides this working access. RAM, ROM and cache have different jobs.

When an application opens, the parts currently needed are loaded from secondary storage into RAM.

Multiple choice1 mark

Why does a computer need primary storage?

  • ATo give the CPU quick access to data and instructions
  • BTo save every user file permanently
  • CTo provide unlimited capacity
  • DTo connect every device to the internet

1. RAM and ROM

RAMROM
PurposeData and instructions currently in use.Fixed instructions or reference data needed by a device.
Contents during useRead and changed.Normally read rather than changed.
Power removedContents lost: volatile.Contents retained: non-volatile.

Firmware is software built into a device to control its hardware. ROM can hold computer start-up instructions or the fixed control program in an embedded system. It can also hold fixed settings used by that program.

ROM is not the normal place for a user's editable photos and documents.

RAM and ROM: contents and power RAM holds currently used data and instructions and loses its contents without power. ROM holds fixed firmware or reference data and retains its contents without power. RAM: working memory Data and instructions in use Read and changed during processing Power off → contents lost ROM: fixed information Firmware or fixed reference data Normally read during ordinary use Power off → contents retained
Fill in the blanks4 marks
RAM is Answer 1. ROM is Answer 2. RAM is normally Answer 3. ROM can retain Answer 4 without power.
  • volatile
  • non-volatile
  • read and write
  • fixed instructions
  • a network connection
Written answer2 marks

Give two differences between RAM and ROM. For each difference, compare both memories.

Students type their answer here.

2. Cache

Cache is small, fast memory in or close to the CPU. It holds frequently or recently used data and instructions.

When a needed item is already in cache, the CPU can access it more quickly than from RAM. Cache reduces waiting; it does not replace the larger working space in RAM.

Multiple choice1 mark

Which statement correctly distinguishes cache from RAM?

  • ACache is larger and slower than RAM
  • BCache permanently holds all applications
  • CCache is smaller and faster to access than RAM
  • DRAM performs calculations

3. Apply the purpose

A music player uses RAM for sound data it is playing now. Its ROM can hold fixed instructions needed to start the device.

An applied answer identifies what is stored and links it to the task.

Written answer2 marks

A student edits a photo on a computer. Give one example of something held in RAM and explain why it is there.

Students type their answer here.

Written answer2 marks

A computer is switched on after being disconnected from power. Explain why ROM is suitable for its start-up instructions.

Students type their answer here.

Written answer1 mark

An oven has a fixed control program and a maximum safe temperature. State one item of information its ROM could hold.

Students type their answer here.

Fill in the blanks2 marks
Answer from memory. (a) Memory holding data currently being edited: Answer 1. (b) Memory retaining fixed start-up instructions without power: Answer 2.
Written answer2 marks

Explain how cache can reduce the time the CPU waits for data or instructions.

Students type their answer here.

Multiple choice1 mark

Unsaved changes are held in RAM when power is lost. Why are those changes lost?

  • ARAM is read only
  • BRAM is volatile
  • CROM has copied them to a disk
  • DCache can only hold instructions