GCSE (9-1) Computer Science
Mark Scheme
J277/01: Units of Data Storage
Question Answer Marks Guidance
1a
  • Nibble (1)
  • Kilobyte (KB) (1)
  • Megabyte (MB) AND Terabyte (TB) in correct places (1)
 3
AO1 (Knowledge)
Examiner Note: The J277 specification explicitly includes Nibble and Petabyte. Ensure students do not miss Nibble between Bit and Byte.
Accept standard abbreviations (MB, TB) even if not written in full.
Phonetic spelling is allowed (e.g., "Megabit" is incorrect, but "Megabite" is typically BOD/Benefit of Doubt).
1b 4 (bits) 1
AO1 (Knowledge)
J277 defines a nibble explicitly as 4 bits.
1c 8 (bits) 1
AO1 (Knowledge)
J277 defines a byte explicitly as 8 bits.
2a 2 TB 1
AO2 (Application)
Examiner Note: 2 TB = 2000 GB, which is clearly larger than 2 GB. 2000 KB is only 2 MB.
2b
  • Computers use binary / switches that are on or off (representing 1 bit) (1).
  • Large amounts of data are grouped into units (like bytes) to make it easier for humans to understand/calculate (1).
 2
AO1 (Knowledge)
Must reference the binary nature of computers (1s and 0s).
3a 2000 (or 2048) 1
AO2 (Application)
Examiner Note: J277 guidance states: "Use of 1,024 for conversions and calculations would be acceptable".
Calculation must use 1000 (e.g. 2 x 1000).
3b 3000 (or 3072) 1
AO2 (Application)
Calculation must use 1000 (e.g. 3 x 1000).
OCR 2026