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 1010 0100 to denary.
Award one mark for:
164
Why: Correct: 128 + 32 + 4 = 164 (1).
37
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.
An operating system manages the users of a computer.
Describe how an operating system checks that a user is allowed to log in.
Award up to two marks for a linked description such as:
Do not award for 'it asks for a password' on its own, without saying what the password is checked against.
A stored list/file of users and passwords with no check of the login details earns one mark only.
Do not accept responses about file management, such as finding or opening the user's files.
The user types in a username and password. The operating system compares these with the details it has stored for that account, and if they match the user is allowed to log in.
Why: Username and password entered (1) which is compared with the account details the operating system has stored (1).
The operating system has a list of all the users and their passwords.
Why: The stored list of users and passwords (1), but no check of the login details against it, so the development mark is not earned (0); the mark scheme states a list alone earns one mark only.
The operating system finds the user's files on the hard drive and opens the last one they saved.
Why: Describes file management, not checking a user's login details; the mark scheme says not to accept responses about file management, so there is 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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