Learn IT: using simple language and everyday examples to study.
This article uses a human body analogy to explain the five core components of computer hardware—CPU as brain, memory as workbench, storage as bookshelf, input/output as senses and expression—plus buses and motherboard, showing how data flows from input through processing to output in a von Neumann architecture.
This article traces the evolution of computing from ancient abacus and mechanical calculators through electronic tube, transistor, and integrated circuit eras to modern PCs, smartphones, supercomputers, and quantum computers, explaining core concepts like automatic program execution and stored-program architecture.
This article explains the classic producer-consumer synchronization problem using a milk tea shop analogy, detailing three solutions—semaphores, monitors, and message passing—with code examples, constraints, variants, and real-world applications like print queues and web servers.
This article explains the classic Dining Philosophers deadlock problem, illustrates why naive locking causes deadlock with code, and presents five solutions—waiter semaphore, odd-even ordering, atomic acquisition, resource hierarchy, and monitor—each with pseudocode, trade-offs, and real-world analogies like database connection pools.
This article explains PV operations (semaphores) using traffic light analogies, covering P/V definitions, mutual exclusion, synchronization, resource counting, the producer-consumer problem with complete code walkthrough, and critical pitfalls like deadlock from incorrect P-ordering.
This article explains major process scheduling algorithms including FCFS, Round Robin, Priority, SJF, HRRN, multilevel feedback queues, and real-time schedulers, with concrete examples, Gantt charts, turnaround/wait time calculations, and a survey of Linux schedulers from O(n) to CFS and EEVDF.
The article explains the three fundamental process states—Running, Ready, Blocked—their characteristics, how they convert between each other, the role of the Process Control Block, Linux‑specific state extensions, and provides illustrative code and diagrams to clarify OS scheduling concepts.
The article explains the LRU (Least Recently Used) page‑replacement algorithm, its basis in the locality principle, hit‑rate example, various exact and approximate implementations—including counter, stack, linked‑list, Clock, Aging and Working‑Set methods—its hardware requirements, pros and cons, and practical uses such as a Python cache and Redis eviction policies.
When a device runs out of RAM, page replacement algorithms decide which pages to evict; the article defines page replacement, outlines goals, compares OPT, FIFO, LRU and their approximations, explains the Belady anomaly, and shows real‑world uses in Linux, JVM GC, and Redis.
The article explains segment‑paging memory management by comparing pure paging, pure segmentation, and their combination, detailing address translation, two‑level page tables, Linux implementation, and practical scenarios such as process layout inspection, fragmentation handling, and protection mechanisms.
