Computer Science OCR AS level QUESTIONS AND ANSWERS
1. Give an example of assembly code: LMC
2. Give an example of a high-level language: C
3.Pseudocode: Pseudocode is not a programming language, it is a simple way of describing a set of
instructions that does not have to use specific syntax.
4.Dry running: A dry run is the process of a programmer manually working through their code to trace
the value of variables. There is no software involved in this process.
5. Variables: Stores numbers, letter and special characters
6. Sequence: Is the execution of statements or functions one after another. (Do this - then this - then thi
7.Selection: Is where the flow through a program is interrupted and control is passed to another
point in the program. The decision is based on a Boolean expression.
8. Iteration: In computer programming, this is a single pass through a set of instructions.
9. HLT (LMC): Stop (Little Man has a rest)
10. ADD (LMC): Add the contents of the memory address from the accumulator
11. SUB: Subtract the contents of the memory address from the accumulator
12. STA or STO (LMC): Store the value in the accumulator
13. LDA (LMC): Load the accumulator with the contents of the memory address given
14. BRA (LMC): Branch always - use the address given as the address of the next instruction
15. BRZ (LMC): Branch to the address given if the accumulator is 0
16. BRP (LMC): Branch to the address given if the accumulator is 0 or positive
,17. INP or OUT (LMC): Input or output, Take from Input if address is 2, copy to output if address
2
18. OTC (LMC): Output the accumulator as a character if address is 22. (Non-standard instruction)
19. DAT (LMC): Used to indicate a location that contains data
20. What does = mean in LMC: Assignment
21. What does == mean in LMC: Checking if equal to
22.Local variable: Variable declared is inside the function, only available to that function. This type of
variable can only be read or modified by the subroutine itself.
23.Global variable: Variable declared outside functions available to whole functions. This type of
variable is available for any part of the code to read and modify
24. What is the life time of the local variable: Function only
25. What is the life time of the global variable: Whole program
26. What are the two different types of functions: • Predefined standard library
functions
• User defined function
,27.What is a predefined standard library function: Functions which already have
a definition in header files so we just call them whenever there is a need to use them e.g. Printf (),
scanf ()
28. What is a user defined function: The function that the programmer create in a progra
29. Why use functions: Re-usable
What is the difference between a function and procedure: Procedure has
30.
no return value but function has a return value
31.What is an IDE: Integrated Development Environment. It helps programmers to code by
having many ditterent features e.g. Adding a closed bracket when you type in an open bracket, colour co-
ordinating and many more
32. What is a debugger: Fixes the bugs (mistakes)
33. Abstraction: A concept of reality e.g. Clock.
What does abstraction commonly make use of: Symbols to represent the
34.
components of a problem therefore the human mind and computing agent can process the problems
What does abstraction also do: Abstraction is also about teasing out what does and what
35.
does not matter in scenario
36. What are the different types of abstract: Digital and analogue
37. Modulisation: Breaking things down
38. Specialisation: Outsourcing things so people who are specialised in that certain department can
that job
, 39. Why is planning important to do: Because then you can order things and know
what you want to do. You could also see which people can do which tasks. This would make it more
suflcient and easier to do the complete task.
40.Serial file: 1 record at a time that goes through every single record but if it doesn't exist, it will just
go to the end. It takes a long time. As it is in no order, the record would not need to be in an exact place so it
could just be added on.
41. Sequential file: 1 record at a time BUT in any chosen order e.g. Alphabetical order. Searches it
in the order and as soon as it goes past the place it should be in the order, it stops. It takes less time than
serial so it is quicker. As it is in an order, the record would need to be in an exact place so the whole file
would need to be altered and cannot just be added on.
42.Why is index used: Index is used to provide quicker searches. An example could be
searching for a topic in a book. This allows searching for a record at a given starting point.
43. Is index a file type?: It is not a file type, it is a sequential file with indexing.
44.If searching for something that doesn't exist, how would serial do
this?: Goes through every record e.g. 2 minutes and then it realised it doesn't exist
1. Give an example of assembly code: LMC
2. Give an example of a high-level language: C
3.Pseudocode: Pseudocode is not a programming language, it is a simple way of describing a set of
instructions that does not have to use specific syntax.
4.Dry running: A dry run is the process of a programmer manually working through their code to trace
the value of variables. There is no software involved in this process.
5. Variables: Stores numbers, letter and special characters
6. Sequence: Is the execution of statements or functions one after another. (Do this - then this - then thi
7.Selection: Is where the flow through a program is interrupted and control is passed to another
point in the program. The decision is based on a Boolean expression.
8. Iteration: In computer programming, this is a single pass through a set of instructions.
9. HLT (LMC): Stop (Little Man has a rest)
10. ADD (LMC): Add the contents of the memory address from the accumulator
11. SUB: Subtract the contents of the memory address from the accumulator
12. STA or STO (LMC): Store the value in the accumulator
13. LDA (LMC): Load the accumulator with the contents of the memory address given
14. BRA (LMC): Branch always - use the address given as the address of the next instruction
15. BRZ (LMC): Branch to the address given if the accumulator is 0
16. BRP (LMC): Branch to the address given if the accumulator is 0 or positive
,17. INP or OUT (LMC): Input or output, Take from Input if address is 2, copy to output if address
2
18. OTC (LMC): Output the accumulator as a character if address is 22. (Non-standard instruction)
19. DAT (LMC): Used to indicate a location that contains data
20. What does = mean in LMC: Assignment
21. What does == mean in LMC: Checking if equal to
22.Local variable: Variable declared is inside the function, only available to that function. This type of
variable can only be read or modified by the subroutine itself.
23.Global variable: Variable declared outside functions available to whole functions. This type of
variable is available for any part of the code to read and modify
24. What is the life time of the local variable: Function only
25. What is the life time of the global variable: Whole program
26. What are the two different types of functions: • Predefined standard library
functions
• User defined function
,27.What is a predefined standard library function: Functions which already have
a definition in header files so we just call them whenever there is a need to use them e.g. Printf (),
scanf ()
28. What is a user defined function: The function that the programmer create in a progra
29. Why use functions: Re-usable
What is the difference between a function and procedure: Procedure has
30.
no return value but function has a return value
31.What is an IDE: Integrated Development Environment. It helps programmers to code by
having many ditterent features e.g. Adding a closed bracket when you type in an open bracket, colour co-
ordinating and many more
32. What is a debugger: Fixes the bugs (mistakes)
33. Abstraction: A concept of reality e.g. Clock.
What does abstraction commonly make use of: Symbols to represent the
34.
components of a problem therefore the human mind and computing agent can process the problems
What does abstraction also do: Abstraction is also about teasing out what does and what
35.
does not matter in scenario
36. What are the different types of abstract: Digital and analogue
37. Modulisation: Breaking things down
38. Specialisation: Outsourcing things so people who are specialised in that certain department can
that job
, 39. Why is planning important to do: Because then you can order things and know
what you want to do. You could also see which people can do which tasks. This would make it more
suflcient and easier to do the complete task.
40.Serial file: 1 record at a time that goes through every single record but if it doesn't exist, it will just
go to the end. It takes a long time. As it is in no order, the record would not need to be in an exact place so it
could just be added on.
41. Sequential file: 1 record at a time BUT in any chosen order e.g. Alphabetical order. Searches it
in the order and as soon as it goes past the place it should be in the order, it stops. It takes less time than
serial so it is quicker. As it is in an order, the record would need to be in an exact place so the whole file
would need to be altered and cannot just be added on.
42.Why is index used: Index is used to provide quicker searches. An example could be
searching for a topic in a book. This allows searching for a record at a given starting point.
43. Is index a file type?: It is not a file type, it is a sequential file with indexing.
44.If searching for something that doesn't exist, how would serial do
this?: Goes through every record e.g. 2 minutes and then it realised it doesn't exist
