Given the definition of what an OS does, why didn’t early computers need an OS?

Question

Imagine Frankie has a computer with a full hard drive. She needs to create and save a new document, so she deletes a bunch of old files, then writes and saves the document. Describe how the OS interacts with the disk to allow the new file to be written.
Imagine you just finished saving an Excel spreadsheet of your budget for the month of January in the year 2016. What would be an especially good name for that file, especially if it’s going into a folder with other similar spreadsheets for other months?
What are the relative benefits and drawbacks of lossy versus lossless compression? Under what circumstances or situations might lossy compression make the most sense? Under what circumstances or situations might lossless compression make the most sense?
Provide three distinct pieces of advice you would give to novice computer users when it comes to how they should name files and/or structure directories on their computer. For each piece of advice, explain the rationale behind it.

Answer 1

Why Early Computers Didn't Need an OS

Early computers were often single-purpose machines that performed very specific tasks, and they were typically operated directly by users or engineers. The programs were written in machine code and loaded directly into the machine's memory. Since these computers only needed to execute one program at a time and had no complex interaction between multiple software applications, an Operating System (OS) was unnecessary. Each task was run manually, and hardware resources were often not shared or required management, allowing for direct control over the system's capabilities.

OS Interaction with the Disk

When Frankie deletes old files to make space on her hard drive, the Operating System steps in to manage this process:

1. Deletion: The OS marks the space occupied by the deleted files as free, updating the file allocation table (FAT) or similar structures that keep track of file locations on the disk. The actual data may still exist temporarily until it's overwritten by new data.

2. File Creation: When she writes a new document, the OS allocates a segment of the free space identified previously. It checks for available disk space by referencing the updated allocation structures.

3. Data Writing: The OS communicates with the disk hardware through drivers to write the document's data to the specified location. It transfers the data in blocks and coordinates with the disk's read/write heads, managing caching and buffering to optimize performance.

4. Updating Metadata: After the file is saved, the OS updates file system metadata, recording the new file's name, size, and location on the disk, ensuring that it's accessible for future retrieval.

Good File Naming for the Spreadsheet

A good name for the Excel spreadsheet containing the January 2016 budget would be: "2016-01_Budget.xlsx". This naming convention is beneficial because:

• Clarity: It specifies the year and month, making it immediately clear what the document contains.
• Sortability: Using the format "YYYY-MM" enables better chronological sorting.
• Consistency: Following this pattern with other monthly files (e.g., "2016-02_Budget.xlsx") promotes easy location and organization.

Benefits and Drawbacks of Lossy vs. Lossless Compression

Lossy Compression:

• Benefits:

  • Reduces file sizes significantly, making them easier to store and transmit.
  • Useful for media where perfect quality is less critical, like web images or streaming audio.

• Drawbacks:

  • Deterioration of quality, which may be noticeable in some cases (e.g., audio artifacts).
  • Not suitable for files requiring exact replicas (e.g., medical images or legal documents).

• Best Situations for Use: Streaming services, web graphics, or any environments where bandwidth and storage are limited, and some quality loss is acceptable (e.g., typical social media images).

Lossless Compression:

• Benefits:

  • Preserves the original quality of files; the data can be perfectly reconstructed from the compressed form.
  • Ideal for documents, text files, and formats like PNG for graphics, where detail is essential.

• Drawbacks:

  • Typically results in larger file sizes compared to lossy compression.
  • Not ideal for media applications where size is a significant constraint.

• Best Situations for Use: Archiving important documents, any usage that requires maintaining data integrity (e.g., medical imaging), or when compressing text files.

Advice for Novice Computer Users on Naming Files and Structuring Directories

1. Use Descriptive and Consistent Naming Conventions:

   • Rationale: Descriptive names (e.g., “Project_X_Report_Sep2023.docx”) provide clarity on what the file contains without needing to open it. Consistency helps in organizing files systematically, which makes future searches easier.

2. Organize Files into Folders Based on Categories or Projects:

   • Rationale: Using folders (e.g., “Work”, “Personal”, “Projects”) allows for easier navigation and grouping of related files. It prevents clutter on the desktop and enables users to find files quickly, thereby increasing productivity.

3. Incorporate Dates in Filenames for Version Control:

   • Rationale: Adding dates (e.g., “Budget_Report_2023-01-15.xlsx”) helps track revisions and updates. It allows users to manage different versions of a document easily and ensures there's a systematic way to identify the most recent versions, reducing confusion over which file to use.