SYSTEM DESIGN AND IMPLEMENTATION IN OPERATING SYSTEM

SYSTEM DESIGN AND IMPLEMENTATION:

This topic deals with the problems faced while designing system and implementation.

The first problem in designing is defining the goals and specifications of the system.

Design Goal:

• The system is affected by choice of hardware and type of the system(batch,single,multi-user,time-shared,distributed,real-time or general)
• Specifying the requirement is harder
• Requirements is divided into two groups

1. user goal-From users desire the system should be convenient,easy to use,easy to learn,reliable,safe and fast.

2. system goal- system should be easy to design ,implement and maintain,flexible,reliable,error free and efficient

MECHANISMS AND POLICIES:

• Since specification and design of an operating system is highly creative task,software engineering principles help to design the operating system.
• Mechanism :-determines how to do some thing
• Policies:-determines what will be done
• policies are likely to change across places or over time-
• Each change in policy would require a change in the mechanisms.

Implementation:

• Traditionally OS have been written in Assembly language now its written in high level languages like C,FORTRAN
• When OS is written in H.L.L its written faster,more compact,easier to understand and debug
• Disadvantage of writing OS in H.L.L is

1. reduced speed,
2. increased storage requirements

• Once the system is written and is working correctly,complicated routines can be written in assembly language equivalents.