Operating System Exam Notes: Scheduling and Memory Management
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Here are 4тАУ5 line, exam-ready answers for each topic you listed:
Operating System Concepts: Part 1
1. FCFS (First Come First Serve) Scheduling
FCFS is a non-preemptive CPU scheduling algorithm where processes are executed in the order of their arrival. The process that arrives first gets the CPU first. It is simple to implement using a queue. However, it can cause long waiting times and the convoy effect.
2. SJF (Shortest Job First) Scheduling
SJF selects the process with the shortest
Read MoreOperating System Structures and Core Components
1. Types of OS
Operating systems can be classified based on their structure, usage, and capability:
Batch Operating System
- Jobs with similar needs are grouped (batched) and run together.
- No direct interaction between the user and the computer during job execution.
- Goal: Maximize CPU utilization.
- Example: Used in environments that process large, repetitive tasks, like payroll systems.
Time-Sharing (Multitasking) OS
- The CPU switches rapidly between multiple jobs (processes) to give each user the impression
Mastering Modular Programming and Data Structures in C
Unit 4: Modular Programming Concepts
Modular programming is a software design technique that divides a program into smaller, independent, and reusable units called modules or functions. Each module performs a specific task, which helps in organizing, testing, and debugging programs more efficiently. By breaking a large problem into manageable pieces, programmers can focus on one module at a time, reducing complexity and improving readability. Modules can be developed, tested, and maintained separately,
Read MoreRelational Database Theory: Algebra, Calculus, and FDs
SQL Constraints and Implementation
Constraints are rules applied to columns to ensure Data Integrity. They are usually defined during the CREATE TABLE process.
| Constraint | SQL Implementation Example | Purpose |
|---|---|---|
| NOT NULL | name VARCHAR(50) NOT NULL | Ensures a column cannot have an empty value. |
| UNIQUE | email VARCHAR(50) UNIQUE | Ensures all values in a column are different. |
| PRIMARY KEY | id INT PRIMARY KEY | Uniquely identifies each row (implies NOT NULL + UNIQUE). |
| FOREIGN KEY | dept_id INT REFERENCES Dept(id) | Ensures the value exists |
Buffer Overflow and Arbitrary Code Execution: Causes & Defenses
Arbitrary Code Execution (ACE)
Arbitrary Code Execution (ACE): A vulnerability where an attacker supplies input to a program such that the CPU interprets that input as executable instructions and runs it. The CPU cannot distinguish between legitimate program code and malicious injected code. Once ACE happens, the attacker controls instruction flow; security boundaries are effectively gone and the system executes whatever the attacker wants.
Buffer Overflow (BO)
BO (Buffer Overflow): All buffer overflows
Read MoreDBMS Architecture, Roles, and Interfaces
Database Interfaces
A DBMS provides various interfaces to suit different types of users (from non-technical clerks to expert administrators).
- Menu-Based Interfaces: Primarily used for web clients and browsing. Users are presented with a list of options (menus) and do not need to know any query language.
- Forms-Based Interfaces: Common for “naive users.” Users interact by filling out fields in a form (e.g., a bank account registration form). The DBMS then handles the insertion or retrieval.
- Graphical