1.8. Operating-System Design and Implementation

1.8.1. Design Goals

• At the highest level, system design is dominated by the choice of hardware and system type.

• Beyond this level, the requirements can be divided into two groups: user goals, and system goals.

  • User goals include convenience, reliability, security, and speed.
  • System goals include ease of design, implementation, maintenance, flexibility, and efficiency.

1.8.2. Implementation

• At first, operating systems were written in assembly, but now 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 interrupts on and off and the Test and Set Instruction for Synchronization Facilities.
• Using higher level languages allows the code to be written faster. It also makes the OS much easier to port to different hardware platforms.