1. Learning outcomes 2 Developing Code – Input Output Model
You must be able to:
explain simple algorithms in terms of their inputs, processing and outputs
determine the purpose of simple algorithms
demonstrate an understanding that more than one algorithm can be used
to solve the same problem
compare the efficiency of algorithms, explaining how some algorithms are more
efficient than others in solving the same problem
obtain user input from the keyboard
output data and information from a program to the computer display.
© Steve Cushing 2016

2. Inputs, processing and outputs
2 Developing Code – Input Output Model
Inputs, processing and outputs
A computer can be described using a simple model as shown on the next slide.
The input stage represents the flow of data into the process from outside the system.
The processing stage includes all tasks required to effect a transformation of the inputs.
The output stage is where the data and information flow out of the transformation process.
© Steve Cushing 2016

3. 2 Developing Code – Input Output Model
© Steve Cushing 2016

4. More than one algorithm can be used to solve the same problem
2 Developing Code – Input Output Model
More than one algorithm can be used to solve the same problem
There will always be a number of methods to solve the same problem, but you always need to create ordered steps to solve any of these problems.
What makes the best solution and what would lead to the best algorithm?
The first criteria we need to consider is does the solution:
work
complete its task in a finite or reasonable amount of time?
© Steve Cushing 2016

5. Comparing the efficiency of algorithms
2 Developing Code – Input Output Model
Comparing the efficiency of algorithms
The next step is to determine which of our solutions is the best or most efficient.
There are generally two criteria used to determine whether one computer algorithm is better than another and these are:
the space requirements (such as how much memory is needed to complete the task)
the time requirements (such as how much time it will take to complete the task).
© Steve Cushing 2016

6. User input from the keyboard
2 Developing Code – Input Output Model
User input from the keyboard
We can get user input by calling this in our code. In AQA pseudo-code we use the following syntax:
USERINPUT
© Steve Cushing 2016

7. Output data and information from a program to the computer display
2 Developing Code – Input Output Model
Output data and information from a program to the computer display
We can send to a display by calling this in our code. In AQA pseudo-code we use the following syntax:
OUTPUT
© Steve Cushing 2016

8. Input/output User input USERINPUT Example a ← USERINPUT
2 Developing Code – Input Output Model
Input/output
User input
USERINPUT
Example  
a ← USERINPUT
© Steve Cushing 2016

9. Output OUTPUT StringExp Example OUTPUT a
2 Developing Code – Input Output Model
Output
OUTPUT StringExp
Example
OUTPUT a
© Steve Cushing 2016