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OCR H446 1.4.1 Data representation consolidation
Part 10 of 11 · H446 1.4.1 · Data types
No new content is introduced here: this is the consolidation piece that pulls the whole of H446 1.4.1 together. A live-event system mixing bookings, lighting values, signed sensor readings, audio, permission flags and messages means the questions never say which method to use, so students have to route to it themselves, starting from closed-book retrieval.
Students will:
- select the right representation method when the question does not name it
- move between denary, 8-bit binary and hexadecimal in a mixed conversion table
- interpret signed readings and complete fixed-width additions with the carry working shown
- normalise and add values in the OCR floating-point format
- read a shift or mask operation and state both the result and its purpose
Inside: 4 explanation cells, 1 multiple-choice question, 1 fill-in-the-blanks cell, 2 written answers and 6 number answers. 42 marks, about 55 to 70 minutes.
Series: H446 1.4.1 · Data types, part 10 of 11.
Shared by Coding PathwayVerified teacher
- 14 cells
- About 60 minutes
- CC BY-SA 4.0
- Shared 31 Aug 2026
- Updated 1 Oct 2026
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The whole resource, exactly as a class sees it. Answers and marking are held back.
Data representation consolidation
Complete the sections in order, beginning with closed-book retrieval and then applying the ideas in the integrated contexts. No new required knowledge is introduced.
A live-event system combines bookings, lighting values, signed sensors, audio, flags and message characters. No new content is introduced.
Retrieval strategy
Before calculating, label the demand: type choice; base conversion; signed interpretation; arithmetic/overflow; floating point; shift/mask; or character mapping. Then write the relevant representation and width. This two-step diagnosis prevents applying a familiar method to the wrong encoding.
Start with the worked routing examples below, then complete the mixed tasks without topic headings.
Stopping point: complete through binary arithmetic in one lesson. Resume with floating point, shifts, masks and character sets in a second lesson or independent study period.
Worked routing examples
- '0074' used as an identifier → String: purpose decides the type.
- 11110000 stated as two’s complement → signed place values, not unsigned conversion.
- mantissa/exponent pair → interpret both fields before arithmetic.
- value AND mask → calculate result, then state selected-bit purpose.
Guided confidence check
For each question, write a two-word method label before working. Identify the required method before continuing.
The value '0074' is a fixed-format ticket identifier and is never used in arithmetic. Which type is most suitable?
- AString
- BInteger
- CReal
- DBoolean
Complete the mixed denary, 8-bit binary and hexadecimal conversion table.
a)Hexadecimal C8. Fill in the denary and binary.
b)Binary 01010010. Fill in the denary and hexadecimal.
c)Denary 231. Fill in the binary and hexadecimal.
d)Binary 00010010. Fill in the denary and hexadecimal.
e)Denary 178. Fill in the binary and hexadecimal.
Interpret each 8-bit two's-complement sensor change in denary.
a)What is the denary value of the two's complement number 11100000?
b)What is the denary value of the two's complement number 10000011?
c)What is the denary value of the two's complement number 10111110?
Add each pair of 8-bit values and retain the carry working.
a)Add these 8-bit binary numbers: 00001111 + 10011010.
b)Add these 8-bit binary numbers: 01010111 + 10000101.
c)Add these 8-bit binary numbers: 01111100 + 00111101.
Normalise each audio value using a 6-bit mantissa and 4-bit exponent.
a)Normalise the floating point number with mantissa 000100 and exponent 0010.
b)Normalise the floating point number with mantissa 000110 and exponent 0011.
c)Normalise the floating point number with mantissa 001101 and exponent 0011.
Add one pair of OCR-format floating-point audio adjustments. Show alignment, mantissa arithmetic and the normalised result.
Add the floating point numbers 011000 (exponent 1101) and 010011 (exponent 1110). Give a normalised answer.
Identify the logical shift direction and number of places in each transformation.
a)10100011 became 00011000. Which shift was applied, and by how many places?
b)00110011 became 00011001. Which shift was applied, and by how many places?
c)01001111 became 00100111. Which shift was applied, and by how many places?
A permissions byte is 11001010 and the system applies OR with 00000101. Give the resulting byte and explain what the mask does.
Separate the bitwise result from the purpose.
Students type their answer here.
The event app expands from English-only notices to messages using many writing systems and emoji. Recommend a character-set approach and justify it.
State a suitable standard and connect its repertoire to the scenario.
Students type their answer here.
Final closed-book checkpoint
Complete each sentence from memory. There is no answer bank and correctness is held for teacher review.
Closed-book review
Choose one completed example from each family and explain the method without looking back.