Computer Science Class Quiz

Hardware and Software

• This is Chapter 2 of a course on hardware and software.
• The chapter covers mainframe computers, supercomputers, system software, utility software, custom-written software, off-the-shelf software, and user interfaces.

Mainframe Computers and Supercomputers

• Characteristics: Longevity, reliability, availability and serviceability (RAS), security, performance metrics (MIPS and FLOPS), volume of input, output and throughput, fault tolerance, operating system, number of processors, heat maintenance.
• Uses (Mainframes): Census, transaction processing, industry statistics, consumer statistics.
• Uses (Supercomputers): Weather forecasting, climate research, quantum mechanics.
• Advantages/Disadvantages: Detailed comparisons between mainframes and supercomputers will be discussed later in the chapter.

Introduction - Mainframe Computers

• Primary use: Bulk data processing for large organizations (censuses, statistics, transactions).
• Characteristics: Larger, more powerful, and more expensive than personal computers.
• Cost: Prices in 2020 started from $75,000
• Functionality: Multitasking and multi-user systems allow many people to work on different tasks simultaneously using hundred of processor cores for parallel processing. Highly reliable and resistant to viruses and Trojan horses.
• Coexistence with PCs: Organizations can use both mainframes and personal computers together, with PCs handling parallel processing tasks, and mainframes maintaining their dominant multitasking capabilities.
• Example: IBM z15 with up to 190 cores.

Introduction - Supercomputers

• Performance: Can have over 100,000 processing cores, exponentially faster than mainframes and PCs (calculations).
• Example: The Summit supercomputer (launched in 2018 in USA), can perform in 1 second what would take the world population 305 days. Occupies a space equivalent to two tennis courts.
• Application: Ideal for large-scale data tasks like payroll batch processing for hundreds of workers in seconds; other examples include applications like weather forecasting and climate research.
• Example: Cray XC40 supercomputer, up to 172000 processor cores

Comparison Summary

• Supercomputers: Designed for maximum computational speed to handle extremely complex, high-level calculations; focus is on scientific research, weather forecasting, simulations, and large-scale data analysis, optimized for a small number of highly complex tasks at very high speed.
• Mainframes: Purpose is built for reliability, multitasking, and managing large-scale data transactions; focused use is in bulk data processing, such as transaction processing, censuses, and business operations, designed to handle a large number of smaller, simple tasks simultaneously.

Characteristics of Mainframe Computers and Supercomputers

• Detailed characteristics (longevity, reliability, security, performance metrics, input/output volumes, fault tolerance, operating systems, processor counts, etc.) are listed independently.

Longevity

• Mainframes: Long lifespan (operating continuously for decades).
• Threats: Older programming languages (e.g., COBOL), skills shortages in maintaining them, technological competition (e.g., cloud computing).
• Comparison to supercomputers: Mainframes generally have a longer lifespan.

Reliability (RAS)

• Reliability: Ability of the system to operate without failure. Mainframes' self-checking processors recover from errors quickly; their software also ensures regular updates.
• Availability: Mainframes are typically operational for extended periods, and can quickly recover from failures, using a process called Mean Time Between Failures (MTBF).
• Serviceability: Easy to identify, diagnose, and resolve issues without major shutdowns.

Security

• Mainframe: Designed to handle sensitive data and is crucial for banking and employee management. It utilizes multi-factor authentication, varying access levels, encryption (of data), secure operating systems.
• Supercomputer: Uses end-to-end encryption to protect sensitive data (e.g., DNA profiles).

Performance Metrics

• Mainframes: Measured in millions of instructions per second (MIPS). MIPS aren't equal due to varying complexities, and benchmarks provide more accurate comparisons. MIPS cost-efficiency is linked to the cost per million instructions per second.
• Supercomputers: Measured in floating-point operations per second (FLOPS). Examples: Petaflops (1 quadrillion), and the expected use of Exaflops (1,000 petaflops) within this decade. FLOPS are more reflective of supercomputer performance than MIPS.

Volume of input, output, and throughput

• Mainframes: Have specialized peripheral processors for input/output (I/O) operations freeing up the central processing unit (CPU) allowing them to manage high volumes of simultaneous input, processing, and output. They handle terabytes of data.
• Supercomputers: Optimized for raw processing power, not throughput.

Fault Tolerance

• Mainframes: High fault tolerance, due to fewer components; Mainframes can automatically switch to alternative processors to maintain functionality.
• Supercomputers: Lower fault tolerance than mainframes due to their large number of components.

Operating system

• Mainframes: Often run multiple operating systems simultaneously, use parallel processing and make efficient use of processor cores.
• Supercomputers: Typically run a single operating system (usually Linux) and employ massively parallel processing, using hundreds of thousands of cores.

Number of processors

• Early Mainframes: Initially had just one processor.
• Mainframes: Typically have hundreds of processor cores.
• Supercomputers: Typically have hundreds of thousands of processor cores.

Heat maintenance

• Mainframes: Early models used liquid cooling and later transitioned to more efficient air cooling for cost savings. Now, liquid cooling is considered more effective for larger models.
• Supercomputers: Often rely increasingly on direct liquid cooling due to the massive heat generated by a large amount of processors.

Uses of Mainframe Computers (including)

• census
• transaction processing
• industry statistics
• consumer statistics

Uses of Supercomputers (including)

• weather forecasting
• climate research
• quantum mechanics

Advantages and disadvantages of mainframe computers and supercomputers

Data Compression

• Lossless: Perfectly restores the original data after decompression. Common for spreadsheet, database, and word processing files. (e.g. GIF, PNG)
• Lossy: Removes unnecessary data bits. Common in image formats and audio files. (e.g. JPEG)
• Advantages: Faster transmission, reduced storage space.
• Disadvantages: Quality reduction in some cases.

Disk Defragmentation

• Process: Rearranging fragmented data blocks on a hard drive to make files contiguous and optimize access times.
• Benefit: Faster file retrieval, improved disk performance, better utilization of disk space.

File copying

• Methods: CLI, GUI
• Result: Duplicate file in different location.

File deleting

• Process: Erasing pointers to locate file.
• Impact: While readily available for deletion, file can still be recoverable until it is overwritten

Anti-virus

• Detection and removal: Identifying and eliminating viruses and other malicious software.
• Prevention: Continuous monitoring for suspicious activity (e.g.; email or file alterations).
• Updates: Regular updates to stay effective against new threats (viruses, adware, worms, Trojan horses).
• Scanning options: Users can scan specific files, folders or the entire system in order to detect threats.
• Automatic scanning: Schedules scans on a regular basis.

Different methods of detecting viruses:

• Signature-based Detection: Matching known virus signatures (byte sequences) and detecting only already known types. Limitations include inability to detect unknown viruses.
• Heuristic-based Detection: Analyzing a program’s source code and comparing it to known viruses. This methods can detect viruses that are not well known, but it can lead to false positives (mistaking harmless files as malware).
• Behavioral-based Detection: Monitoring for unusual behavior that might indicate a virus activity (e.g. sending large numbers of emails, altering critical files), and running suspected malicious software within secure sandbox environments.

Utility Software

• Need and uses: For tasks beyond operating systems
• Examples: File management, Memory management, Data compression, Disk defragmentation, Backup software.

Operating Systems

• Functions: Manage hardware, software, resources, and user interactions for a computer.
• Memory: Allocates RAM to programs.
• Input/output: Manages data from various input/output components.
• Files: Tracks files, space, and details.
• Multitasking: Handles multiple processes/ programs.
• Error Handling: Displays errors to users.
• Security: Protection, encryption, permissions.

Disk Management

• Functionality: Formats (low-level), partitions, compresses, defragments, manages drives, backs up disks.
• Specific Use Cases: Assigns names to disks, initializes drives, extends or shrinks partitions, and changes drive letters.

Custom Written Software

• Use Cases: Designed to meet specific, unique needs. Examples include integrated solutions like websites, databases, and spreadsheets.
• Development Time: Significantly high; development is based on the client specifications and requirements.
• Ownership: Entirely owned by the company purchasing or commissioning the custom-written software.

Off-the-Shelf Software

• Use Cases: Designed for widespread use. Cost-effective if the needs aren't too specific. Examples include programs and packages like payroll, word processing, spreadsheet, database programs.
• Advantages: Cost-effective, immediately readily available, comprehensive support, rigorously tested
• Disadvantages: Potential limitations on customization, might include unnecessary features, compatibility difficulties depending on the client's system.

User Interfaces

• CLI (Command Line Interface): Text-based input; Preferred by developers, administrators, and advanced users needing precise control
• GUI (Graphical User Interface): Windows, icons, menus, pointers; Easy to use for most users; Can use more resources; Learning curve with updates
• Dialogue Interface: Voice-based input; Useful for users with disabilities and certain tasks; possible background noise, and limited vocab.
• Gesture-Based Interface: Physical gestures to control devices; Useful for specific situations (e.g., controlling devices, medical use, gaming)

Test your knowledge on hard disk drives, formatting types, and user interfaces in this comprehensive quiz. Dive into the intricacies of data storage, defragmentation, and the advantages of GUIs. Perfect for students in computer science classes looking to reinforce their understanding.