2.1 computational thinking

Question 1

deifine abstraction

Answer 1

abstraction is the act of removing unecessary details

Question 2

why is abstraction implemented

Answer 2

because it can provide the same quality product while reducing the computational resources required
focus on the purpose of the program
reduce complexity fo the design
reduce programming coplexity
reduce memory requirements

Question 3

define preconditions

Answer 3

Things to consider before creating the solution i.e
budget, time frame, current solution, current hardware, skill set etc

Question 4

what are the three main aspects of thinking ahead

Answer 4

specifying inputs
specifying outputs
preconditions

Question 5

what are the pros of defining preconditions

Answer 5

makes program components reusable
cutting out unecessary checks
makes the program easier to maintain

enhances modularity
reduces errors

Question 6

what are the main programming standards

Answer 6

function shouldnt be longer than a page of code

variable identifiers must stick to a convention

each function must have a single entry point

variable must not be set up ouside the scope of the function (local variables)

Question 7

how do operating systems utalise ‘Thinking ahead’

Answer 7

by caching frequently accessed data
this can be done with prefetching where an algorithm predicts the next data to be fetched and places it in cache before it is fetchied into the CPU

Question 8

pros of caching

Answer 8

faster access
less bandwidth used

Question 9

cons of caching and prefetching

Answer 9

disk thrashing may occur if used to often
there is a chance that the algorithm is wrong and the data prefetched isnt needed next.

Question 10

define decomposition

Answer 10

breaking up the problem into small more managable sub-problems

Question 11

what are the benefits of modularisation

Answer 11

large problems broken down easier to solve

subroutine can be tested individually

modules can be resued in several programs

frequently used modules can saved as libraries

programmers can work concurrently

programs have fewer errors

easier to debug

easier to maintain

Question 12

what does a good algorithm include

Answer 12

clear set of steps to prodice the correct output

is efficient and completed in as few steps as possible

Question 13

how is concurrent processing done

Answer 13

multiple cores
tasks broken down into subtasks

Question 14

pros of concurrent processing

Answer 14

solution found faster
increase program throughput
(rate a system can complete a task)

Question 15

cons of concurrent processing

Answer 15

more memory
more difficult to program

Question 16

difference between parallel processing and concurrent processing

Answer 16

concurrent not actually simultaneously swaps between subtasks quicky
parallel

Question 17

Describe the different ways a programmer could ensure that invalid data entries are not made by the user when selecting a venue and date for a cinema [4]

Answer 17

search box used to populate the venue
drop down menu for all the valid venues

calendar used for date
raneg check to make sure no 13th months

Question 18

when developing a set of applications (like word ppt and excel) why is it good for developers to reuse code [4]

Answer 18

Pre-tested
pre-compiled
saves time and money

similar look
quicker to learn
more comfortable with products in this set
user becomes more productive

Question 19

what is caching

Answer 19

The Process of storing instructions or data in cache memory

Question 20

what is prefetching

Answer 20

operating system predicts the next item that will be fetched and it is pre loaded into cache

Question 21

What are the goals behind thinking abstractly

meaning

Answer 21

identifying what does and doesnt matter
identifying the variables and objects needed
see levels of the problem (diff levels of abstraction)

Question 22

What are the theoretical positives of thinking abstractly

Answer 22

simplifies the probelms/ interface (simplifies it for both the user and the developer)
reduces the computational complexity of the solution
easier to see how he solution could be applied to another problem

Question 23

What are the cons of thinking abstractly

Answer 23

Models wont be as accurate

Question 24

examples thinking abstractly

Answer 24

using icons and symbols
putting data in a chart
moving nodes on a graph to change how it looks

Question 25

define thinking ahead

Answer 25

identifying the preconditions of a system (inputs outputs and reusable components)

Question 26

What does thinking ahead entail

in a general sense

Answer 26

Identifying preconditions

Identifying the state the data needs to be in for the algorithm to work

Identifying what data is required before it’s needed (prefetching)

identifying reusable components

Question 27

What theoretical pros of Caching

Answer 27

Can improve efficiency greatly

Question 28

What are the cons of caching

Answer 28

can be difficult to implement
is only as good as the operating systems predictions
data prefetched not always accurate

Question 29

what does thinking procedurally entail

Answer 29

identifying smaller sub problems
determine the order of sub problems are executed

Question 30

what are the pros of thinking procedurally

Answer 30

problem are easier to solve
debugging is easier

Question 31

What are the cons of thinking proceduraly

Answer 31

may not always be possible
(in an event driven program)

Question 32

define thinking logically

Answer 32

identifying individual steps and decision points of an algorithm

Question 33

Define Concurrently processing

Answer 33

more than one process happening at the same time
(seemingly)

Question 34

what are the pros of concurrent processing

Answer 34

Increase speed

Question 35

what are the cons of concurrent processing

Answer 35

May be difficult to program
Can sometimes result in deadlock
problem may not suit concurrency

Question 36

Go to examples of abstraction

Answer 36

Simplified weather
buildings and trees removed
simplified physics
reduced scenery
etc