Interfaces

Interfaces

1. Hardware

   • Transfer
     • Check current status
     • Request transfer
     • Wait/check for notification/completion
   • Device Drivers
     • Generic interface
       • Open
       • Read
       • Write
       • Close
       • Abstraction to treat all devices the same
     • OS communicate through ports/interrupts/DMA

2. User interface

   • HCI
     • Shells
       • Apps
       • Utilities
       • Dev tools
     • Environment Variables
       • Commonly used configuration values - accessible to any program
     • Settings
     • User Environment
       • Display preferences
       • Application default settings
       • OS default settings
   • Control program
     • CLI
     • GUI
     • Simple scripting interface

3. System Call Interface / API

   • Allows application programs to request OS services
     • Program execution
     • I/O access
     • Read/Write files
     • Each API function invokes a corresponding system call routine
     • Program in user mode accesses hardware/memory via API call
   • Object Libraries
   • Header Files
   • Documentation