Design and Implementation

Design and Implementation

Design:

• Before designing the system, first define goals and specification of the system. Goals and specification will give the idea about the system and it also understands the requirement of the user. At the higher level, system design is dominated by the choice of hardware and system type.

• System type may be batch system, multiprogramming, multitasking, real time and distributed system. Hardware must support all these type of operating system.            

• Once the goal and specification is clearly understood, then a requirement is related to user and system. These requirements are called user goals and system goals.

• User goals are as follows:

1. Simple to use and understand. 

2. Provides reliability.

3. Provides security.

4. Fast speed.

• System goals are as follows:

1. Easy to design

2. Implementation and maintenance is also simple and easy

3. Free from error

4. Efficient to use.

• Operating system requirements is not fixed. It will change according to the user requirements. Single user operating system is required and multiple user operating systems is also required.

Implementation

• At first, operating systems were written in assembly, but now a days C/C++ is the language commonly used.

• Small blocks of assembly code are still needed, especially related to some low level I/O functions in device drivers, turning interrupt on and off and the Test and Set instruction for synchronization facilities.

• Using higher level language allow code to be written faster, is easier to read, and can be debugged easier. It also makes the OS much easier to port to different hardware platforms.