Stories with Tag Operating Systems

• DOS APPEND

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  Posted: 2024-12-20 21:04:59

  Verbose tl;dr

  DOS APPEND, similar to the PATH command, allows you to specify directories where DOS should search for data files, not just executable files. This lets programs access data in various locations without needing full path specifications. It supports both drive letters and network paths, and offers options to search appended directories before the current directory or to treat appended directories as subdirectories of the current one. APPEND also provides commands to display the current appended directories and to remove them. This expands the functionality beyond the simple executable search of PATH, making data access more flexible.

  The blog post "DOS APPEND" from the OS/2 Museum meticulously details the functionality and nuances of the APPEND command in various DOS versions, primarily focusing on its evolution and differences compared to the PATH command. APPEND, much like PATH, allows programs to access data files located in directories other than their current working directory. However, while PATH focuses on executable files, APPEND extends this capability to data files, specified by various file extensions.

  The article begins by explaining the initial purpose of APPEND in DOS 3.3, highlighting its ability to search specified directories for data files when a program attempts to open a file not found in the current directory. This eliminates the need for programs to explicitly handle path information for data files. The post then traces the development of APPEND through later DOS versions, including DOS 3.31, where a significant bug related to networked drives was addressed.

  A key distinction between APPEND and PATH is elaborated upon: PATH affects only the search for executable files (.COM, .EXE, and .BAT), while APPEND pertains to data files with extensions specified by the user. This difference is crucial for understanding their respective roles within the DOS environment.

  The blog post further delves into the various ways APPEND can be used, outlining the command-line switches and their effects. These switches include /E, which loads the appended directories into an environment variable, /PATH:ON, which enables searching the appended directories even when a full path is provided for a file, and /PATH:OFF, which disables this behavior. The post also explains the use of /X, which extends the functionality of APPEND to affect the EXEC function calls, thus influencing child processes.

  The evolution of APPEND continues to be discussed, noting the removal of the problematic /X:ON and /X:OFF switches in later versions due to their instability. The article also touches upon the differences in behavior between APPEND in MS-DOS/PC DOS and DR DOS, particularly concerning the handling of the ; delimiter in the APPEND list and the search order when multiple directories are specified.

  Finally, the post concludes by briefly discussing the persistence of APPEND in later Windows versions for compatibility, even though its utility diminishes in these more advanced operating systems with their more sophisticated file management capabilities. The article thoroughly explores the intricacies and historical context of the APPEND command, offering a comprehensive understanding of its functionality and its place within the broader DOS ecosystem.

  • DOS
  • OS/2
  • APPEND
  • command-line
  • Operating System
  • file system
  • path
  • environment variable
  • IBM
  • Retrocomputing
  • vintage computing
  • MS-DOS
  • PC DOS
  • Disk Operating System
  • Operating Systems
  • IBM PC
  • command interpreter
  • search path

  Summary of Comments ( 56 )
  https://news.ycombinator.com/item?id=42475011

  Verbose tl;dr

  Hacker News users discuss the DOS APPEND command, primarily focusing on its obscure nature and surprising functionality. Several commenters recall struggling with APPEND's unexpected behavior, particularly its ability to make files appear in directories where they don't physically exist. The discussion highlights the command's similarity to environment variables like PATH and LD_LIBRARY_PATH, with one user pointing out that it effectively extends the file search path for specific programs. Some comments mention the utility of APPEND for accessing data files across drives or directories without hardcoding paths, while others express their preference for more modern solutions. The overall sentiment suggests APPEND was a powerful but complex tool, often misunderstood and potentially problematic.

  The Hacker News post titled "DOS APPEND" with the link https://www.os2museum.com/wp/dos-append/ has several comments discussing the utility of the APPEND command in DOS and OS/2, as well as its quirks and comparisons to other operating systems.

  One commenter recalls using APPEND frequently and finding it incredibly useful, particularly for accessing data files located in different directories without having to constantly change directories or use full paths. They highlight the convenience it offered in a time before sophisticated development environments and integrated development environments (IDEs).

  Another commenter draws a parallel between APPEND and the modern concept of environment variables like $PATH in Unix-like systems, which serve a similar purpose of specifying locations where the system should search for executables. They also touch on how APPEND differed slightly in OS/2, specifically regarding the handling of data files versus executables.

  Further discussion revolves around the intricacies of APPEND's behavior. One comment explains how APPEND didn't just search the appended directories but actually made them appear as if they were part of the current directory, creating a virtualized directory structure. This led to some confusion and unexpected behavior in certain situations, especially with programs that relied on obtaining the current working directory.

  One user recounts experiences with the complexities of managing multiple directories and files in early versions of Turbo Pascal, illustrating the context where a tool like APPEND would have been valuable. This comment also highlights the limited tooling available at the time, emphasizing the appeal of features like APPEND for streamlining development workflows.

  Someone points out the potential for conflicts and unexpected results when using APPEND with programs that create files in the current directory. They suggest that APPEND's behavior could lead to files being inadvertently created in a directory different from the intended one, depending on how the program handled relative paths.

  The security implications of APPEND are also addressed, with a comment mentioning the risks associated with accidentally executing programs from untrusted directories added to the APPEND path. This highlights the potential security vulnerabilities that could arise from misuse or improper configuration of the command.

  Finally, there's a mention of a similar feature called apppath in the REXX language, further illustrating the cross-platform desire for this kind of directory management functionality.

  Overall, the comments paint a picture of APPEND as a powerful but somewhat quirky tool that provided a valuable solution to directory management challenges in the DOS/OS/2 era, while also introducing potential pitfalls that required careful consideration. The discussion showcases how APPEND reflected the computing landscape of the time and how its functionality foreshadowed concepts that are commonplace in modern operating systems.

• Why did Windows 95 setup use three operating systems?

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  Posted: 2024-11-17 19:54:24

  Verbose tl;dr

  Windows 95's setup process involved three distinct operating systems to ensure a smooth transition and maximize compatibility. It began booting from a DOS-based environment to provide basic hardware access and initiate the installation. Then, a minimal Windows 3.1-like environment took over, offering a familiar GUI for interacting with the setup program and allowing access to existing drivers. Finally, the actual Windows 95 operating system was installed and booted, completing the setup process and providing the user with the full Windows 95 experience. This multi-stage approach allowed the setup program to manage the complex transition from older systems while providing a user-friendly interface and maintaining compatibility with existing hardware and software.

  Raymond Chen's blog post, "Why did Windows 95 setup use three operating systems?", delves into the intricate, multi-stage booting process employed by the Windows 95 installation procedure. Rather than a straightforward transition, installing Windows 95 involved a complex choreography of three distinct operating systems, each with a specific role in preparing the system for the final Windows 95 environment.

  The initial stage utilized the existing operating system, be it DOS or Windows 3.1. This familiar environment provided a stable launching point for the installation process, allowing users to initiate the setup program from a known and functional system. Crucially, this initial OS handled the preliminary steps, such as checking system requirements, gathering user input regarding installation options, and initiating the transfer of files to the target hard drive. This ensured that the subsequent stages had the necessary foundation upon which to build.

  The second operating system introduced in the Windows 95 installation was a minimalist DOS-based environment specifically designed for setup. This stripped-down DOS lacked the complexities and potential conflicts of a full-fledged DOS installation, providing a predictable and controlled environment for the core installation tasks. This specialized DOS environment executed directly from the installation media, circumventing potential issues arising from the existing operating system and allowing for low-level access to the hardware necessary for partitioning and formatting the hard drive, as well as copying the essential Windows 95 system files. It operated independently of the pre-existing operating system, ensuring a clean and controlled installation environment.

  Finally, the third operating system involved was the actual Windows 95 operating system itself. Once the setup-specific DOS environment completed the file transfer and preliminary configuration, the system rebooted, this time loading the newly installed Windows 95. This first boot of Windows 95 was not merely a functional test, but an integral part of the installation process. During this initial boot, Windows 95 performed crucial configuration tasks, including detecting and installing hardware drivers, finalizing registry settings, and completing any remaining setup procedures. This final stage transitioned the system from the installation environment to a fully operational Windows 95 system ready for user interaction.

  In essence, the Windows 95 installation process leveraged a tiered approach, employing the existing OS for initial setup, a specialized DOS environment for core file transfer and low-level configuration, and finally the Windows 95 OS itself for final configuration and driver installation. This multi-stage process ensured a robust and reliable installation, mitigating potential conflicts and providing a clean transition to the new operating system. This complexity, while perhaps not immediately apparent to the end user, was a key factor in the successful deployment of Windows 95.

  • Windows 95
  • Setup
  • Operating Systems
  • MS-DOS
  • Windows 3.1
  • Bootstrapping
  • Installation Process
  • Legacy Systems
  • Microsoft
  • Windows History
  • Real Mode
  • Protected Mode
  • Boot Process
  • Legacy OS
  • Installation
  • x86
  • 16-bit
  • 32-bit
  • x86 Architecture

  Summary of Comments ( 192 )
  https://news.ycombinator.com/item?id=42166606

  Verbose tl;dr

  Hacker News commenters discuss the complexities of Windows 95's setup process and the reasons behind its use of MS-DOS, a minimal DOS-based environment, and a pre-installation environment. Several commenters highlight the challenges of booting and managing hardware in the early 90s, necessitating the layered approach. Some discuss the memory limitations of the era, explaining the need to unload the DOS environment to free up resources for the graphical installer. Others point out the backward compatibility requirements with existing MS-DOS systems and applications as another driving factor. The fragility of the process is also mentioned, with one commenter recalling the frequency of setup failures. The discussion touches upon the evolution of operating system installation, contrasting the Windows 95 method with more modern approaches. A few commenters share personal anecdotes of their experiences with Windows 95 setup, recalling the excitement and challenges of the time.

  The Hacker News post "Why did Windows 95 setup use three operating systems?" generated several comments discussing the complexities of the Windows 95 installation process and the technical reasons behind using MS-DOS, a 16-bit preinstallation environment, and the 32-bit Windows 95 itself.

  Several commenters focused on the bootstrapping problem inherent in installing a new operating system. They pointed out that a simpler OS is required to launch the installation of a more complex one. MS-DOS served this purpose in the Windows 95 setup, providing a familiar and readily available platform to begin the process. The discussion included how the initial boot from floppy disk would load a basic DOS environment, which would then launch the next stage of the installation.

  The role of the 16-bit preinstallation environment was also discussed. Commenters explained that this environment, distinct from both MS-DOS and the final Windows 95 system, was crucial for tasks that couldn't be handled by the limited DOS environment, such as accessing CD-ROM drives and managing more complex hardware configurations. This intermediary step allowed the setup to gather information about the system, prepare the hard drive, and begin copying the necessary Windows 95 files.

  Some commenters delved into the technical limitations of MS-DOS, highlighting its 16-bit architecture and inability to directly handle the 32-bit components of Windows 95. The preinstallation environment bridged this gap, providing the necessary functionality to transition to the 32-bit world. This discussion touched upon the complexities of real-mode and protected-mode memory addressing, which were relevant to the transition between these different environments.

  The specific use of three separate systems was a point of interest. Some commenters speculated about alternative approaches, but acknowledged the practical constraints of the time. The existing familiarity with MS-DOS made it a logical starting point. The distinct preinstallation environment provided a dedicated space for setup-specific tasks without interfering with the final Windows 95 installation.

  A few comments also touched on the nostalgia associated with the Windows 95 installation process and the challenges of managing hardware configurations in that era. The need to manually configure drivers and settings was highlighted, contrasting sharply with the more automated installation processes of modern operating systems.