00.1 (conspect) Challenges of OS and disadvantages of Assembler language
- Operating system (OS)
- is system software that manages computer hardware, software resources, and provides common services for computer programs (how to operate computer).
Functions:
- Separation
- Unification
- Account (fair consumption)
Resources:
- Operative memory(RAM) - Serves for time data storage with which the central processor works
- Processor time (measure of how much time the processor spends on any particular process, expressed in a ratio)
- Peripherals (внешние устройства такие как звуковая карта)
Multitasking
History:
- Batch mode (mode of skipping and simultaneous processing of user tasks - programs entered from external media or the terminal, taking into account their priorities and resources required by them) : Single Tasking
- Substituting multitasking (preemptive multitasking is a type of multitasking where the operating system decides to switch between tasks after a certain quantum of time has elapsed) : division of time, device lockdown
- Multiplayer mode : access sharing (including memory)
OS monolithic architecture:
- Kernel (The kernel is a computer program that is the core of a computer's operating system, with complete control over everything in the system) : implementation mechanisms (unification, separation, accounting «УРУ»)
- User space: logic of unification, separation, accounting and solving of user’s subtasks (for example, programming libraries - math libraries in c++/python);
- Computer applications: optional OS component for solving of the user task
C programming language
Disadvantages of assembler language:
- Call agreements of subtask
- Register planning / three types of variables - static, on stack and registers
- System call wrapper (numbers, various IT parameters, etc.)
- Arithmetic expressions
- Circuits and Conditional Operators
- Address arithmetic
- Compiling data types
What needs to be left behind:
- Actual memory/addressing model : The memory model corresponds to the hardware model (addresses)
- Scalar data types correspond to hardware
- The order of bytes in the machine word and its digit capacity