Sequence
Programs follow a clear sequence. Take a brief program to convert a temperature from Celsius into Fahrenheit as an example.
Line 1 - RECEIVE celsiusTemp FROM (INTEGER) KEYBOARD
Line 2 - SET fahrenheitTemp TO (celsiusTemp * (9/5)) + 32
Line 3 - SEND fahrenheitTemp TO DISPLAY
Here are 3 lines of code.
The first line gets a temperature from the user and stores it in a variable called 'celsiusTemp'.
The second line converts the temperature from Celsius to Fahrenheit and then stores it in a variable called 'fahrenheitTemp'.
The third line displays the converted temperature.
Line 1 would run, then line 2, then line 3. The program would not try to run the code on line 3 before the code on lines 1 and 2.
Computer systems rely heavily on the input, process, output cycle. In the temperature conversion example, the three steps were:
| Input | Line 1 - Get the user to input the temperature in Celsius |
| Process | Line 2 - Process the temperature into Fahrenheit |
| Output | Line 3 - Output the temperature in Fahrenheit to the screen |
| Input |
| Line 1 - Get the user to input the temperature in Celsius |
| Process |
| Line 2 - Process the temperature into Fahrenheit |
| Output |
| Line 3 - Output the temperature in Fahrenheit to the screen |
The input, process, output cycle is often evident in our everyday use of computer systems. On a mobile phone, when you press a character key when typing a message, the software on your phone takes that input, processes it and then outputs the character on screen.
