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MCA Articles
Page 7 of 95
Apple iOS Architecture
iOS is the operating system created by Apple Inc. for mobile devices. iOS powers many Apple mobile devices such as iPhone, iPod, and iPad. It is the second most popular mobile operating system globally, trailing only behind Android in market share. The iOS architecture follows a layered design pattern. It contains intermediate layers between applications and hardware, ensuring they do not communicate directly. The lower layers provide basic system services, while higher layers offer user interface components and sophisticated graphics capabilities. iOS Architecture Overview iOS Architecture Layers ...
Read MoreSystem Calls in Unix and Windows
System calls provide the interface between a process and an operating system. They are available as assembly language instructions and serve as the only mechanism for user programs to access kernel services. System calls are similar to function calls but transfer control from user mode to kernel mode. How System Calls Work When a process needs operating system services, it makes a system call which triggers a software interrupt. The CPU switches from user mode to kernel mode, executes the requested service, and returns the result to the calling process. This mechanism ensures security and controlled access to ...
Read MoreOperating System Debugging
Operating System Debugging is the systematic process of identifying, analyzing, and resolving issues within computer systems. Modern operating systems employ various debugging mechanisms to maintain system stability and help developers diagnose problems effectively. Log Files Log files serve as comprehensive records of system activities, capturing events, errors, and state changes. The operating system writes structured messages to these files, creating an audit trail for troubleshooting and system analysis. Types of Log Files Log Files ...
Read MoreLoadable Modules Architecture of the Operating System
Loadable kernel modules are object files containing code that extends the running kernel (also called the base kernel) of an operating system. These modules provide a flexible way to add support for new file systems, hardware drivers, system calls, and other kernel functionality without modifying the core kernel code. Loadable modules allow the operating system to dynamically load and unload kernel components as needed, making the system more modular and efficient. Loadable Modules Architecture Base Kernel Core OS Functions ...
Read MoreWhat is Zombie Process in Linux?
A zombie process is a process whose execution is completed but it still has an entry in the process table. Zombie processes usually occur for child processes, as the parent process still needs to read its child's exit status. Once this is done using the wait() system call, the zombie process is eliminated from the process table. This is known as reaping the zombie process. Zombie Process Life Cycle Parent Process Child Process ...
Read MoreWhat are the different states of a Process?
A process is an active program under execution. It includes the program counter, process stack, registers, and program code, making it more comprehensive than just the static program code (text section). A process passes through different states during its execution lifecycle. While these states may vary across operating systems, the fundamental process states are standardized. The diagram below illustrates the common process states and their transitions − Process State Diagram New Ready ...
Read MoreWhat is user-defined signal handler?
User-defined signal handlers are custom functions that programmers write to override the default behavior when specific signals occur in a program. Signals are software interrupts sent to indicate important events, and they can be handled in two ways: using default signal handlers or user-defined signal handlers. Types of Signal Handlers Default signal handler − Built-in system behavior for each signal type User-defined signal handler − Custom function written by the programmer to handle specific signals User-defined signal handlers allow programs to customize their response to signals rather than relying on default system actions. Different signals ...
Read MoreCritical Section Problem
The critical section problem occurs when multiple processes access shared resources concurrently. A critical section is a code segment where shared variables can be accessed. To maintain data consistency, only one process can execute in its critical section at a time — this requires an atomic operation. All other processes must wait to execute in their critical sections. Critical Section Structure Process 1 Entry Section Critical Section ...
Read MoreThe Benefits of Multithreaded Programming
Multithreading allows the execution of multiple parts of a program at the same time. These parts are known as threads and are lightweight processes available within the process. So multithreading leads to maximum utilization of the CPU by multitasking. Threads within a process share the same memory space but have their own execution context, including program counter, stack, and registers. This enables efficient parallel execution while maintaining data sharing capabilities. Key Benefits of Multithreaded Programming Benefits of Multithreaded Programming Multithreading ...
Read MoreRunning vs Waiting vs Terminated Process
A process is an active program under execution. It is more than just program code as it includes the program counter, process stack, registers, and program code. As a process executes, it transitions through different states based on its current activity and resource availability. The process state diagram illustrates how processes move between different states during their lifecycle − Process State Diagram NEW READY RUNNING ...
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