Computer Systems Quiz - Chapter 1.1

1.1 Computer Systems

• Processor Structure and Function: The control unit manages instruction execution, coordinating data flow. The arithmetic logic unit (ALU) performs arithmetic and logical operations. Registers are small, fast storage for intermediate data, like the program counter for instruction tracking and accumulators for results. Cache is high-speed storage for frequently accessed data, improving speed. Buses (data, address, control) coordinate actions.

• Fetch-Decode-Execute Cycle: The processor fetches an instruction from memory using the program counter, decodes it into control signals, then executes the instruction.

• CISC vs. RISC Processors: Complex Instruction Set Computing (CISC) processors have a large instruction set, making programming easier, but slower. Reduced Instruction Set Computing (RISC) processors use a simplified instruction set, resulting in faster and more efficient processing, requiring more instructions.

• Parallel Processing: Using multiple cores or processors for simultaneous tasks boosts performance in multi-threaded applications.

1.1.3 Input, Output, and Storage

• Input Devices: Convert user input to digital signals. Examples include keyboards, microphones, and sensors.

• Output Devices: Present processed data to users. Examples include monitors, speakers, and printers.

• Primary Storage: RAM is volatile memory, used for temporary data storage during processing. ROM is non-volatile, holding permanent data (like the BIOS).

• Secondary Storage: HDDs (magnetic) are cost-effective for large capacities, but slower. SSDs (Flash) are faster and more durable, but more expensive per GB. Tertiary storage is for archiving and backups (e.g., optical discs, magnetic tape).

1.2 Software Development

• Systems Software (OS): Acts as an interface between hardware and software. Key functions include memory management, multitasking, and file system handling. Examples include Windows, macOS, and Linux.

• Utility Software: Performs maintenance tasks (e.g., antivirus, disk defragmentation, file compression).

• Application Software (Types): Custom software is tailored to specific user needs. Off-the-shelf software provides general solutions. Open-source software is free and modifiable. Proprietary software is licensed and not available for modification, examples including Microsoft Office, and Adobe Photoshop.

• Software Development Stages: Initial analysis of user needs and constraints. Followed by designing a solution using diagrams and pseudocode. This is followed by implementing code using a suitable programming language. Thorough testing (white-box and black-box) evaluates internal logic and program outputs. Maintenance includes corrective actions, adapting to new environments, and enhancing features.

• Programming Methodologies: Waterfall uses a linear sequential approach, good for small, well-defined projects. Agile is iterative and collaborative.

1.2.4 Types of Programming Languages

• Low-Level Languages: Machine code uses binary instructions directly by the CPU. Assembly language uses readable mnemonics.

• High-Level Languages: Python and Java are easier to code and debug, more portable across systems.

• Declarative Languages: Focus on the desired outcome, rather than specifying steps. SQL for databases demonstrates this.

• Imperative Languages: Specify step-by-step instructions for solving problems.

1.3 Data Representation, Encryption, and Networks

• Compression: Lossless compression perfectly reconstructs original data, while lossy reduces file size by discarding non-essential data.

• Encryption: Symmetric encryption uses the same key for encryption/decryption. Asymmetric uses separate keys for security. Applications include securing online transactions.

• Hashing: Converts input data into fixed-size hashes for data integrity checks. Password storage uses this method.

• Databases: Primary Keys uniquely identify records. Foreign keys ensure relationships between tables. Normalization reduces data redundancy. SQL is used for data manipulation and database structure definition.

1.3.3 Networks

• Network Types: LAN connects devices in a limited area, while WAN connects devices over larger distances (internet).

• Network Topologies: A star topology uses a central hub, and a mesh topology connects devices directly for redundancy.

• Network Protocols: HTTP/HTTPS manage web communication. FTP handles file transfers. SMTP manages email communication.

• Network Security: Firewalls block unauthorized access. VPNs secure remote access. MAC address filtering restricts access to authorized devices.

1.4 Computational Thinking and Programming

• Data Types: Common data types include integers, floating-point numbers (real), Booleans, characters, and strings. Casting converts from one data type to another.

• Data Structures: Arrays use contiguous memory locations, efficient for indexed access. Stacks are Last-In, First-Out. Records group related data. Linked Lists have dynamic memory allocation for inserting and deleting data. Queues are First-In, First-Out, useful in scheduling. Graphs and trees represent relationships between data for quick searching or sorting.

• Programming Concepts: Variables store data. Looping (for, while) iterates over code blocks. Conditional statements (if-else) make decisions in code execution. Functions modularize code. Recursion helps solve problems through smaller instances of the overall problem.