Build a practice paper from 693 exam-style questions, each with its mark scheme and example answers. Print it, or answer it on paper and then open the mark schemes. Or browse the questions by topic.
3 questions · 5 marks
Computers manipulate binary patterns.
Convert the binary pattern 1110 0000 to denary.
Award one mark for:
224
Why: Correct: 128 + 64 + 32 = 224 (1).
7
Why: Reads the place values from the wrong end (the left-hand bit as 1), so the value is wrong.
3
Why: Counts the 1s instead of adding their place values.
A computer can be used by more than one person.
Describe how an operating system uses access rights to protect each user's files.
Award up to two marks for a linked description such as:
Do not accept responses about asking for a password/username, as this checks who the user is, not what they are allowed to do.
Do not accept 'files are protected/safe' or 'access rights protect files' without saying how access is limited (e.g. read-only access, permissions for different users).
A user can be given read-only access to a file, so they can open it but cannot edit or delete it.
Why: Read-only/read access point (1) and linked development that the user cannot edit/delete the file (1).
A user can be given read-only access to a file.
Why: Read-only/read access point (1); no development saying what this prevents, such as being unable to edit/delete the file (0).
The operating system asks for the password again before the file opens.
Why: Describes asking for a password, which checks who the user is, not access rights to the file; no creditworthy point.
A high-level program must be translated into machine code before it can be run.
Describe how a compiler and an interpreter differ in when the translated code is executed.
Award up to two marks for a linked description such as:
Allow 'translates one line at a time' where it is linked to executing each line immediately.
Do not accept answers that only state that a compiler is faster/an interpreter is slower, without reference to when execution happens.
Do not accept answers that only give object code, error reporting or portability, without reference to when execution happens.
Do not accept the compiler executing the program as it translates it.
The compiler translates the code first and the program is executed afterwards, but the interpreter executes each line as soon as it has been translated.
Why: Compiler translates the whole program first and it is executed afterwards (1) and interpreter executes each line as soon as it is translated (1).
The interpreter executes each line immediately after translating it.
Why: Correct interpreter timing (1); no comparison with when the compiler's translated code is executed.
The compiler executes the program line by line as it translates it.
Why: Reverses the two translators; a compiler does not execute the program it translates, so no mark.
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