Software Layers: Operating system, Drivers, System Software, Application programs
Software layer
Operating System
> OS receives order from the user via application program
> It has programs and routines that control all accesses to hardware
> Higher levels are protected from any issues
- Multiple users
- Multiple requests for the same resource
- Access control
> When the OS determines its safe to proceed, direct calls to device drivers are performed
System software
> What is system software?
> Type of system software:
- Operating systems
- Utility programs
> Operating system = a set of programs that coordinates all the activities among computer hardware resources
> Utility programs = a set of programs that allows a user ti perform maintenance - type concerning the computer itself, its devices and its programs
Low - Level Language
> Two type:
- Machine Language
- Assembly Language
> Machine language = the first generation PL
> Assembly language = the second generation PL
Machine language
> Uses a series of binary digits (1s and 0s) or combination of numbers and letters that represent binary digits
> The binary digits corresponds to the ON and OFF electrical states
Assembly Language
> Program is written using symbolic instruction codes called mnemonic
> Also uses symbolic memory addresses
> Assembly language must be converted into machine language before the computer can execute the program
Standard Software packages : Overview and typical installation procedures
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