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1CP2-P-2.7 Signed data and encoding checkpoint
Part 7 of 7 · 1CP2-P-2 · Signed data and encoding
The checkpoint for the whole series, sampling two's complement, shifts, hexadecimal and character encoding together.
Students will:
- interpret and represent 8-bit two's complement patterns
- apply both a logical and an arithmetic shift correctly
- explain the precision consequences of each shift type
- convert between binary and hexadecimal and justify the notation
- explain why 7-bit ASCII cannot serve a worldwide database
Inside: 6 explanation cells, 1 multiple-choice question, 5 number cells, 1 fill-in-the-blanks cell and 3 written answers. 20 marks, about 45 minutes.
Series: 1CP2-P-2 · Signed data and encoding, part 7 of 7.
Shared by Coding PathwayVerified teacher
- 16 cells
- About 45 minutes
- CC BY-SA 4.0
- Shared 17 Aug 2026
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The whole resource, exactly as a class sees it. Answers and marking are held back.
Signed data and encoding checkpoint
This checkpoint assesses only 1CP2-P-2. It contains no programming-strand questions. Concise method reminders precede new values and contexts.
1. Two's complement
Use signed place values to interpret a pattern. To represent a negative value, write the positive magnitude in eight bits, invert every bit, add one, then cross-check. Eight-bit range: −128 to +127.
Interpret these 8-bit two's complement patterns.
Enter the signed denary values.
a)What is the denary value of the two's complement number 11100111?
b)What is the denary value of the two's complement number 10010110?
Represent these denary values in 8-bit two's complement.
Enter only the final patterns.
a)Write −45 as an 8-bit two's complement number.
b)Write −120 as an 8-bit two's complement number.
2. Binary shifts
Logical shifts insert zeroes. Arithmetic right shift copies the sign bit. A left shift relates to multiplication by a power of two only while the result fits; a right shift can discard remainder information.
Apply a logical left shift by two places.
Move all bits left, insert two zeroes and retain the fixed eight-bit width.
Apply a logical shift left of 2 places to 00010111.
Apply an arithmetic right shift by two places to this signed pattern.
Copy the original sign bit into both vacated positions.
Apply a arithmetic shift right of 2 places to 11010000.
Explain why a logical right shift can make an unsigned integer less precise, and why arithmetic right shift uses a different fill rule for a negative two's-complement value.
Address both discarded remainder bits and sign preservation.
Students type their answer here.
3. Hexadecimal
One hexadecimal digit maps to one four-bit nibble. Convert each nibble independently. Hexadecimal is human shorthand for the same binary pattern; it does not reduce storage.
Convert these binary patterns to hexadecimal.
Use two four-bit nibbles.
a)Convert 10001111 to hexadecimal, one nibble at a time.
b)Convert 01101010 to hexadecimal, one nibble at a time.
Explain why hexadecimal is used to display long binary patterns, and identify one incorrect claim that should be avoided.
Link fewer written symbols to a human benefit.
Students type their answer here.
4. Character representation
Seven-bit ASCII provides 128 codes. A character set maps each supported character to a numeric code stored in binary. Wider encodings provide more codes for more scripts and symbols.
- 68
- 128
- fewer
- more
Explain why 7-bit ASCII is unsuitable as the only character set for a worldwide names database.
Connect capacity to scripts and symbols.
Students type their answer here.
Which statement connects all four topics accurately?
- AEvery bit pattern has one fixed meaning in every context.
- BRepresentation rules determine whether bits are a signed number, shifted value, hexadecimal shorthand or character code.
- CHexadecimal and ASCII both remove bits from storage.
- DArithmetic shifts convert characters into numbers.
Series complete
You have consolidated signed conversion and range, applied and explained logical and arithmetic shifts, converted binary and hexadecimal, and explained 7-bit ASCII and wider encoding needs. These ideas will be retrieved later in data representation and systems contexts.