GCSE COMPUTER SCIENCE OCR STUDY GUIDE EXAM
QUESTIONS AND ANSWERS SURE A+
✔✔Accumulator - ✔✔A register inside the CPU which holds the running total or result of
the current instruction.
✔✔Address Bus - ✔✔A physical wire which transmits memory addresses between the
CPU and the RAM
✔✔Data Bus - ✔✔A physical wire which transmits data between the CPU and the RAM
✔✔Binary Search - ✔✔Takes the median of a sorted list, and if it is greater than the
input, then the top half of the list is removed, and a new list is created until the correct
match is found.
✔✔Efficiency of algorithms - ✔✔Speed, Size, Storage
✔✔Bubble Sort - ✔✔Easy to code, however with a longer list can be very inefficient
✔✔Name Five Data Types - ✔✔Integer, Real, Boolean, String, Character
✔✔Definite Iteration - ✔✔Repeating the process until a desired result with a finite
number of iterations, that is calculable. Do Until - Loop
✔✔Indefinite Iteration - ✔✔Repeating an iteration that is conditional, and may be
repeated infinitely. While-End While
✔✔Nested Selection - ✔✔A selection within a selection
✔✔= - ✔✔Equal to
✔✔<> - ✔✔not equal to
✔✔< - ✔✔less than
✔✔> - ✔✔greater than
✔✔Abstraction - ✔✔Abstraction is the process of removing all unnecessary information
from a set of instructions so that the aim of the instructions is not distracted from and so
that the final product is as good as possible. The abstracted data is simpler and more
relevant to the operation. Abstraction can speed up the program.
✔✔<= - ✔✔less than or equal to
, ✔✔>= - ✔✔greater than or equal to
✔✔Dry Run - ✔✔The program is run on paper and each stage is carefully analyzed to
see what values the various variables have. At this stage, a computer is not being used.
✔✔Input - ✔✔Information given to the program, used in the algorithm
✔✔Output - ✔✔Information returned from the completed task
✔✔Processing - ✔✔Using the inputted data to perform the task and return the
manipulated information
✔✔Overflow Error - ✔✔A calculation produces a result that is greater than the computer
can deal with or store with the available number of bits
✔✔Linear Search - ✔✔It is a simple, sequential search. It starts at the beginning of the
list and moves through the items, on by one, until it finds the matching value or reaches
the end without finding one.
✔✔Trace Table - ✔✔While the dry run is being worked through, a table is drawn up
showing the values of each variable, input and output, and how they change as the
program is running. A trace table has columns for each of the steps in the algorithm.
✔✔What does a Binary Search do? - ✔✔Searches an ordered list to find an item by
looking at the median and comparing it with the search value. (if the item needed is
bigger then it reduces the list to all the values it can still be and begins this cycle again)
✔✔What is a Bubble Sort? - ✔✔A Bubble sort puts a group of random numbers in
order.
✔✔Merge Sort - ✔✔Sorts unordered list by repeatedly (recursively) dividing the list into
two smaller lists until the size of each list becomes 1. The individual lists are then
merged.
✔✔True Colour - ✔✔Set to 24 bits per pixel- 8 bits per colour (Red, green or blue), 8
bits allows for 256^3 (16777216) variations of the colour, this provides a realistic image
that is as close to what we naturally see as the computer can get it.
✔✔Colour Depth - ✔✔The number of bits used to encode the colour of each picture
element
✔✔Pixel - ✔✔A picture element which is the smallest dot or point of colour in an image
or on a computer screen
QUESTIONS AND ANSWERS SURE A+
✔✔Accumulator - ✔✔A register inside the CPU which holds the running total or result of
the current instruction.
✔✔Address Bus - ✔✔A physical wire which transmits memory addresses between the
CPU and the RAM
✔✔Data Bus - ✔✔A physical wire which transmits data between the CPU and the RAM
✔✔Binary Search - ✔✔Takes the median of a sorted list, and if it is greater than the
input, then the top half of the list is removed, and a new list is created until the correct
match is found.
✔✔Efficiency of algorithms - ✔✔Speed, Size, Storage
✔✔Bubble Sort - ✔✔Easy to code, however with a longer list can be very inefficient
✔✔Name Five Data Types - ✔✔Integer, Real, Boolean, String, Character
✔✔Definite Iteration - ✔✔Repeating the process until a desired result with a finite
number of iterations, that is calculable. Do Until - Loop
✔✔Indefinite Iteration - ✔✔Repeating an iteration that is conditional, and may be
repeated infinitely. While-End While
✔✔Nested Selection - ✔✔A selection within a selection
✔✔= - ✔✔Equal to
✔✔<> - ✔✔not equal to
✔✔< - ✔✔less than
✔✔> - ✔✔greater than
✔✔Abstraction - ✔✔Abstraction is the process of removing all unnecessary information
from a set of instructions so that the aim of the instructions is not distracted from and so
that the final product is as good as possible. The abstracted data is simpler and more
relevant to the operation. Abstraction can speed up the program.
✔✔<= - ✔✔less than or equal to
, ✔✔>= - ✔✔greater than or equal to
✔✔Dry Run - ✔✔The program is run on paper and each stage is carefully analyzed to
see what values the various variables have. At this stage, a computer is not being used.
✔✔Input - ✔✔Information given to the program, used in the algorithm
✔✔Output - ✔✔Information returned from the completed task
✔✔Processing - ✔✔Using the inputted data to perform the task and return the
manipulated information
✔✔Overflow Error - ✔✔A calculation produces a result that is greater than the computer
can deal with or store with the available number of bits
✔✔Linear Search - ✔✔It is a simple, sequential search. It starts at the beginning of the
list and moves through the items, on by one, until it finds the matching value or reaches
the end without finding one.
✔✔Trace Table - ✔✔While the dry run is being worked through, a table is drawn up
showing the values of each variable, input and output, and how they change as the
program is running. A trace table has columns for each of the steps in the algorithm.
✔✔What does a Binary Search do? - ✔✔Searches an ordered list to find an item by
looking at the median and comparing it with the search value. (if the item needed is
bigger then it reduces the list to all the values it can still be and begins this cycle again)
✔✔What is a Bubble Sort? - ✔✔A Bubble sort puts a group of random numbers in
order.
✔✔Merge Sort - ✔✔Sorts unordered list by repeatedly (recursively) dividing the list into
two smaller lists until the size of each list becomes 1. The individual lists are then
merged.
✔✔True Colour - ✔✔Set to 24 bits per pixel- 8 bits per colour (Red, green or blue), 8
bits allows for 256^3 (16777216) variations of the colour, this provides a realistic image
that is as close to what we naturally see as the computer can get it.
✔✔Colour Depth - ✔✔The number of bits used to encode the colour of each picture
element
✔✔Pixel - ✔✔A picture element which is the smallest dot or point of colour in an image
or on a computer screen
