Computer system anywhere must employ one chain of operation; input → process → output.
Computer system work
Weather forecast input output
Think of the data that human can gain from weather forecast. Air pressure, wind direction, wind force, air temperature, humidity are among those inputs that human can gather from weather forecast. Human process these data then output the rain falling probability. Rain falling data input could be one of the information needed by human but according to a computer system it is the only data that it can process.
Without data input
There is a computer system processing without the need of input data. Such system is when human calculate the circumference of a circle to a precision of 100 million digits. This kind of processing does not need data input.
Computer program work
The work of a computer program is to construct input process then output. Whenever it comes to complex processing the computer program will break the long process into many parts to be analyzed then take their statistics. Separate good input data from bad one. Take that good data process then save their results before you connect them to the original data statistics like a chain. This one whole chain is called a program and one program output could be an input for another program. Computer system will comprised of many basics processes which follows correct rules. The system engineer will be responsible to divide these complex programs into simpler ones then instruct programmers to do this work.
When human add up number 10 with 20. The output will not be displayed as 10 plus 20 but instead they will use variable name to represent this adding process. Such algorithm can be shown to be as below using variable name such as X, Y, Z etc.
Enter 10 in X
→ enter 20 in Y
→ add up X and Y then enter into Z
→display Z value on screen display
Numerical and text used in variable will be annotated with type. Numerical types and text types both will be different. Inserting numerical in variable will need a = sign, whereas text in variable will be surround by apostrophe. Such as A = "HELLO".
Method presenting flow chart
Method presenting flow chart start and end with rectangle shape with no edges. Input and output comes with parallelogram while process rectangular with edges. Table below shows you each symbol with explanations:
Preparation - It shows the preparation made for influence on command after execute the operation.
Predefined process - It shows the process made by group of commands for more than one defined special place.
Connector - It shows In the same flow chart that connects input or output.
Display - Type of information displays on your screen.
Manual input - Input data done by hand.
Diamond shape symbol defined as decision is most needed during processing information. Input comes from top while two outputs go down. This is shown as:
More on flow charts.