1. Topic 2: Hardware and Software
Systems software

2. Learning Objectives
To explain the purpose of system software (including: compilers, linkers, device drivers, operating systems and utilities, interpreters)
To explain the purpose of system software.

3. What is Systems Software?
Refers to the operating system and all utility programs that manage computer resources:
BIOS (Basic Input Output System)
Compilers
Interpreter
System utilities
System software is the interface between the hardware and user applications
To explain the purpose of system software.

4. Device Drivers To explain the purpose of system software.
A driver is a piece of software that converts commands such as 'print' into instructions that the particular piece of hardware (printer) can understand.
The operating system is usually pre-loaded with drivers for all of the hardware it needs to control.
To explain the purpose of system software.

5. Device Drivers To explain the purpose of system software.
However, as time goes by, new hardware is developed and the operating system won't have the correct driver.
So, the manufacturer of the hardware will provide the correct 'driver' on a CD-ROM or from their website so that you can install it.
To explain the purpose of system software.

6. Utilities To explain the purpose of system software.
A Utility is a piece of software that performs a specific and useful task, for example compressing files, defragmenting the hard disk.
Many utilities come as part of the Operating System.
To explain the purpose of system software.

7. Compilers To explain the purpose of system software.
What does the word compile mean?
Gather resources from many sources to produce something… e.g. a book / report.
To explain the purpose of system software.

8. Compilers To explain the purpose of system software.
Most computer programmers work in what is known as a 'high level' computer programming language such as C++.
This means that the code they write is very readable by humans. For example the command, 'print document' could be a high level command. As you see, it is very easy to see what it should be doing.
To explain the purpose of system software.

9. Compilers To explain the purpose of system software.
But, computers work with binary data, 0's and 1's and it wouldn't understand what 'print document' meant.
So a special piece of software called the 'compiler' will translate the high level instructions into a form that the computer can deal with.
To explain the purpose of system software.

10. Compilers To explain the purpose of system software.
If (score < 30)
Output “fail”
Else if (score >=30)
Output “pass”
Compiler
Machine Code
To explain the purpose of system software.

11. Interpreters To explain the purpose of system software.
These are executable programs.
The program has been compiled
and an ‘.exe’ file has been generated.
To explain the purpose of system software.

12. Interpreters
To explain the purpose of system software.

13. Interpreters To explain the purpose of system software.
Websites are not executed. Instead a browser interprets (reads) the HTML (web language) and the browsers displays the page. It is read 1 line at a time.
To explain the purpose of system software.

14. Interpreters
There are two ways computer code is run - the first way is to run the code as an 'executable'.
This means that the code is loaded into memory and then allowed to run within the CPU by the operating system.
To explain the purpose of system software.

15. Interpreters To explain the purpose of system software.
But there is a second way - namely code running through an interpreter.
An interpreter accepts program instructions as an input, the interpreter then executes the code one line at a time.
To explain the purpose of system software.

16. Interpreters To explain the purpose of system software.
Disadvantage; is that the code runs slower than an executable code.
Interpreted languages include HTML, ASP.NET (web languages.
To explain the purpose of system software.

17. Linkers To explain the purpose of system software.
This is an .dll file (some code linked to the .exe.)
Dynamic Link Library.
This is an .exe file (the actual program)
To explain the purpose of system software.

18. Linkers To explain the purpose of system software.
Also called link editor and binder, a linker is a program that combines object modules to form an executable program.
Many programming languages allow you to write different pieces of code, called modules, separately.
This simplifies the programming task because you can break a large program into small, more manageable pieces.
To explain the purpose of system software.

19. Linkers

20. Page 42
To explain the purpose of system software.

21. Page 43 – Asks you write what the software is about and an example.