The document discusses operating system design and implementation. It outlines design goals for an operating system including user goals like ease of use and reliability, and system goals which depend on the environment. Implementation is discussed, noting traditionally assembly was used but modern operating systems often use high-level languages like C and C++ due to advantages in development speed, portability and understandability, though assembly is still sometimes used for performance critical routines. Memory management and CPU scheduling are highlighted as important parts of implementation.

1. Operating System Deign
And implementation

2. Design Goals
 First problem in designing system is to define goals and specification
 At highest level design affected by hardware and type of system
 Requirements are much harder to specify
 Requirements are categorized in two groups users goals and system goals
User goals
Convenient ,easy to learn and use ,reliable ,safe , fast
System should easy to design ,create , maintain and update. (os developer)
Flexible , reliable , error free and efficient

3. Design Goals
 System goals
No unique solution to define system goals
Depends on environment
VxWorks: real time OS ,for embedded system
Multiuser System: IBM mainframes

4. Implementation
 Traditionally assembly language
 High level language C, C++
 Master Control Program (MCP)-First OS- variants of ALGOL, MULTICS
 Linux and Windows XP: C , Assembly Language
 High level language: written faster , more compact , easier to understand and debug.
 Improvement in compilation needs only recompilation.
 Easier to port
 MS DOS : Assembly Language –runs on intel x86 family
 Disadvantage : Reduced speed and increased storage requirements
Small Assembly language routines
Modern computers have deep pipelining and multiple functional units

5. Implementation
 Performance improvement – better DS and algorithm than assembly code
 Memory manager and CPU Scheduler