OCR GCSE Computer Science (J277) · Computer systems (Paper 1) › Memory and storage
Practise Units and capacity. 12 exam-style questions plus unlimited generated ones on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
Cover the answers and test yourself. The app has these as flashcards that come back just before you'd forget them.
State the number of bits in one byte.
8
A text document contains 2000 characters. Each character is stored using 1 byte. Calculate the size of the document in bytes.
2000 bytes
A file transfer tool shows the amount downloaded so far in MB, but the app's summary screen shows the total in GB. Use 1 GB = 1000 MB. Calculate 2500 MB in GB.
2.5 GB
Sample questions
Written for this site in the style of OCR exam questions. They are not taken from real past papers.
Question 1Easy3 marks
(a) Which one of the following lists the units in order from smallest to largest? Tick (✓) one box.[1]
nibble, bit, byte, kilobyte
bit, byte, nibble, kilobyte
byte, bit, nibble, megabyte
bit, nibble, byte, kilobyte
(b) State the number of bits in one byte.[1]
(c) State the name of the unit that is equal to 1000 terabytes.[1]
Show the answer and mark scheme
(a)Answer: bit, nibble, byte, kilobyte
(b)Answer: 8
8
(c)Answer: petabyte (PB)
petabyte / PB
Question 2Medium3 marks
(a) Explain why data must be converted into binary before it can be processed by a computer.[2]
(b) Calculate the number of bytes in 2.5 MB. Use 1 MB = 1000 KB and 1 KB = 1000 bytes.[1]
Show the answer and mark scheme
(a)
computers are made of (billions of) switches / transistors / logic gates
which only have two states (on and off), represented by 1 and 0
(b)Answer: 2,500,000 bytes
2,500,000 (bytes)
Question 3Hard4 marks
A student wants to back up these files onto a single USB flash drive:
350 photos, each 4.2 MB
120 songs, each 5 MB
45 videos, each 750 MB
documents with a total size of 850 MB
USB flash drives are available with capacities of 16 GB, 32 GB, 64 GB and 128 GB.
Calculate the total size of the files and identify the smallest USB flash drive that the student could use. Use 1 GB = 1000 MB. Show your working.[4]