7.2 Computer systems, sub-systems anddecomposition

structure diagram: a hierarchical diagram showing the breakdown of a computer program into sub-programs
![](https://doc.tiegg.com/media/202510/802bdfcc350d4d37b814041f1a2ff1514267.png)
Flowchart: a diagram showing the ordered steps to complete a computer program
![](https://doc.tiegg.com/media/202510/83bac95461704ef8a8d735147063e6f34012.png)
Pseudocode: shows what a program does in plain language
##### Data Type

| Data Type | Characteristics/Definition                                                  |        Example         |
| :-------: | :-------------------------------------------------------------------------- | :--------------------: |
|  INTEGER  | A whole number                                                              |         5, -3          |
|   REAL    | A number capable of containing a fractional part                            |        4.7, 0.3        |
|  STRING   | A group of characters consisting of letters, numbers and special characters | "This is a string", "" |
|   CHAR    | A single character                                                          |      ꞌxꞌ, ꞌCꞌ, ꞌ@ꞌ     |
|  BOOLEAN  | The logical values TRUE and FALSE                                           |      TRUE, FALSE       |