Stories with Tag Tricks

• Dirty tricks 6502 programmers use

  permalink

  Posted: 2025-04-16 13:58:36

  Verbose tl;dr

  The 6502 processor, known for its limitations, inspired clever programming tricks to optimize speed and memory. These "dirty tricks" leverage quirks like the processor's behavior during undocumented opcodes, zero-page addressing, and interactions between instructions and flags. Techniques include self-modifying code to dynamically alter instructions, using the carry flag for efficient branching, and exploiting specific instruction timings for precise delays. By understanding the 6502's nuances, programmers could achieve remarkable results despite the hardware constraints.

  This blog post, titled "Dirty tricks 6502 programmers use," delves into a collection of clever and often obscure programming techniques employed by developers targeting the MOS Technology 6502 microprocessor, a popular chip used in systems like the Apple II, Atari 2600, and Commodore 64. These "tricks" leverage intimate knowledge of the 6502's architecture and instruction set to achieve optimized code size and execution speed, often at the expense of readability and maintainability.

  The author begins by explaining the 6502's zero-page addressing mode, which allows for faster and more compact code by referencing memory locations within the first 256 bytes of RAM. This is illustrated with the common practice of storing frequently used variables in this zero-page region. The post then explores more intricate techniques, such as self-modifying code. This involves manipulating the program's own instructions during runtime, a powerful but risky technique allowing for dynamic behavior, like constructing jump tables or altering opcodes based on program state. Specific examples are given demonstrating how this can be used to achieve complex logic with minimal code.

  The post further examines the exploitation of undocumented opcodes, referred to as "illegal" or "undocumented" instructions. These are operations not officially part of the 6502 instruction set, but which nonetheless execute on the hardware, sometimes with unpredictable or processor-specific results. The author emphasizes the potential dangers and portability issues of relying on these undocumented opcodes, while also acknowledging their potential for extreme optimization in certain scenarios. Examples are provided illustrating how these instructions might behave, demonstrating their ability to manipulate processor flags or perform unusual arithmetic operations.

  The use of the 6502's stack for temporary variable storage is another explored trick. While pushing and pulling values on the stack incurs overhead, it can save memory and be more efficient than zero-page access in some cases. The author elaborates on the limitations and cautions involved in managing stack usage carefully. The post also covers techniques for manipulating the processor status register (P) flags directly through specific instructions, which can bypass typical flag setting conditions and lead to smaller and faster code.

  Finally, the author discusses the concept of "bit bashing" which involves directly manipulating individual bits within memory locations. This technique, useful for controlling hardware or managing data structures efficiently, leverages logical operations like AND, OR, and XOR to manipulate bits within bytes. Examples provided demonstrate how this can be used to set, clear, or toggle specific bits. The post concludes by acknowledging the inherent trade-offs associated with these "dirty tricks," emphasizing that while they can be powerful tools for optimization, they often come at the cost of code clarity, maintainability, and portability. It encourages careful consideration of the context before employing such techniques.

  • 6502
  • Assembly Language
  • programming
  • Low-Level Programming
  • optimization
  • Tricks
  • hacks
  • Retrocomputing
  • vintage computing
  • 8-bit
  • MOS Technology
  • Microprocessor
  • Software Development

  Summary of Comments ( 2 )
  https://news.ycombinator.com/item?id=43705649

  Verbose tl;dr

  Hacker News users generally expressed appreciation for the article on 6502 programming tricks, finding it informative and nostalgic. Several commenters shared additional tricks or variations, including using the undocumented SAX instruction and manipulating the stack for efficient data storage. Some discussed the cleverness borne out of the 6502's limitations, while others reminisced about using these techniques in their youth. A few pointed out the techniques' applicability to other architectures or modern resource-constrained environments. There was some debate about the definition of "dirty" vs. "clever" tricks, but the overall sentiment was positive towards the article's content and the ingenuity it showcased. The discussion also touched on the differences between assembly programming then and now, and the challenges of optimizing for limited resources.

  The Hacker News post titled "Dirty tricks 6502 programmers use" (linking to https://nurpax.github.io/posts/2019-08-18-dirty-tricks-6502-programmers-use.html) has generated a modest number of comments, most of which express appreciation for the insights into 6502 programming techniques.

  Several commenters reminisce about their experiences with the 6502, often mentioning specific machines like the Apple II, Commodore 64, and Atari 2600. They share anecdotes about using similar techniques or encountering them in classic games. These nostalgic comments contribute a sense of shared history and community around the 6502.

  Some commenters delve deeper into specific techniques mentioned in the article. One commenter elaborates on the self-modifying code aspect, highlighting its prevalence in 6502 programming due to the architecture's limitations and the creativity it fostered. Another discusses the use of lookup tables for sine/cosine calculations, emphasizing their efficiency on the 6502. There's also discussion about the clever use of the zero page for optimization and the different addressing modes available on the 6502.

  One particular comment thread discusses the difference between "tricks" and simply using the features of the instruction set effectively. The general consensus seems to be that the techniques described are indeed clever uses of the limited resources available, qualifying as justifiable "tricks." This discussion adds a layer of nuance to the conversation, moving beyond simple appreciation to a more analytical examination of the programming practices.

  A few comments mention other resources for learning about 6502 programming and low-level optimization techniques. These recommendations provide additional avenues for readers interested in exploring the topic further.

  While not a large volume of comments, the discussion on Hacker News around this article provides valuable context and insights from experienced programmers, enriching the original article with personal anecdotes, technical explanations, and further learning resources.

• Automating the Vim Workplace (2020)

  permalink

  Posted: 2025-02-09 14:12:51

  Verbose tl;dr

  This blog post details the author's highly automated Vim setup, emphasizing speed and efficiency. Leveraging plugins like vim-plug for plugin management and a variety of others for features like fuzzy finding, Git integration, and syntax highlighting, the author creates a streamlined coding environment. The post focuses on specific configurations and keybindings for tasks such as file navigation, code completion, compiling, and debugging, showcasing a personalized workflow built around minimizing friction and maximizing productivity within Vim. The ultimate goal is to achieve a near-IDE experience using Vim's powerful extensibility.

  Sharad Shardanand's 2020 blog post, "Automating the Vim Workplace," details his comprehensive approach to optimizing his Vim editing environment for maximum efficiency and customization. He outlines a meticulous configuration process, moving beyond basic Vim setup to create a truly personalized and powerful workflow.

  The post begins by emphasizing the philosophy behind his approach: striving for a consistent and reproducible Vim experience across different machines. This is achieved primarily through leveraging a Git repository to manage his Vim configuration files, ensuring easy synchronization and version control. He uses a dedicated .vim directory within his home directory and explains the practice of symlinking this directory to the appropriate Vim configuration location based on the operating system being used.

  A key element of his automation strategy is the use of a plugin manager, specifically vim-plug, to streamline the installation and updating of plugins. He describes the benefits of vim-plug, including its parallel installation capabilities and on-demand loading functionality, which contributes to a faster startup time for Vim. The post provides detailed examples of how to configure vim-plug within the init.vim file, showcasing how to define and manage various plugins based on file types and personal preferences.

  Shardanand then delves into the specific plugins he employs to enhance his Vim workflow. These include plugins for syntax highlighting, file browsing, code completion, Git integration, and more. He explains the rationale behind choosing each plugin, illustrating how they contribute to a more productive and enjoyable editing experience. For example, he highlights the use of NERDTree for improved file navigation and ctrlp for fuzzy file finding within projects. The configuration details for each plugin are meticulously documented, providing readers with practical examples to replicate the setup.

  Beyond plugin management, the post discusses other crucial aspects of his Vim configuration. He elaborates on customizing keybindings for specific commands and actions, streamlining common tasks and movements within the editor. He also explains how to configure color schemes and themes, enabling a personalized and visually appealing interface. Furthermore, he demonstrates how to set up auto-completion and linting capabilities within Vim, improving coding efficiency and reducing errors.

  Finally, the post addresses the management of multiple Vim configurations tailored for different scenarios. He discusses using conditional logic within the init.vim file to activate specific plugins and settings based on the context, such as working on a specific project or operating system. This enables a highly adaptable and dynamic Vim environment.

  In essence, Shardanand's post provides a comprehensive guide to creating a robust and personalized Vim setup. He emphasizes automation through Git, plugin management with vim-plug, and meticulous configuration of plugins, keybindings, and themes. The detailed explanations and practical examples offered make it a valuable resource for both novice and experienced Vim users looking to enhance their editing workflow.

  • vim
  • Automation
  • workflow
  • productivity
  • Editor
  • Text Editor
  • scripting
  • vimscript
  • Plugins
  • Extensions
  • 2020
  • Tips
  • Tricks
  • Customization
  • configuration

  Summary of Comments ( 25 )
  https://news.ycombinator.com/item?id=42990801

  Verbose tl;dr

  Hacker News users generally praised the author's approach to Vim automation, emphasizing the balance between leveraging Vim's powerful features and avoiding over-complication. Several commenters shared their own preferred plugins and workflows, highlighting tools like fzf, vim-projectionist, and CtrlP for file navigation, and luasnip and UltiSnips for snippets. Some appreciated the author's philosophy of learning Vim gradually and organically, rather than attempting to master everything at once. A few commenters discussed the trade-offs between using a highly configured Vim setup versus a more minimalist approach, and the potential drawbacks of relying too heavily on plugins. There was also a brief discussion about the relative merits of using language servers and other external tools within Vim.

  The Hacker News post titled "Automating the Vim Workplace (2020)" with the ID 42990801 has several comments discussing various aspects of Vim automation and related topics.

  A significant portion of the discussion revolves around the trade-offs between automating everything within Vim and using external tools or shell scripts. Some commenters advocate for the power and efficiency of keeping actions within Vim, leveraging its built-in capabilities and plugins for tasks like project management and file manipulation. They argue this approach maintains focus and avoids context switching. One commenter specifically mentions using Vim for tasks like creating Github issues and managing TODO lists, emphasizing the benefit of a unified workflow. Another highlights the speed advantage of Vim's internal commands compared to external tools, particularly for smaller tasks. This speed is attributed to avoiding the overhead of launching external processes.

  Conversely, other commenters argue for the flexibility and power of shell scripting and external tools. They point out that shell scripts can be more easily composed and reused, and they provide access to a wider range of functionalities. One commenter specifically suggests using make for complex project automation, citing its robust dependency management capabilities. This perspective suggests that while Vim excels at text editing, dedicated tools are better suited for broader automation tasks. Another comment emphasizes the importance of choosing the right tool for the job, advocating against forcing all tasks into the Vim environment.

  The discussion also touches on specific Vim plugins and tools. One commenter mentions using projectionist.vim for project management within Vim, while others discuss the benefits and drawbacks of different approaches for tasks like compiling code and running tests.

  A few comments delve into more specific technical details, such as the use of Vim's built-in functions for file manipulation and the integration of Vim with external tools through plugins and scripts. One commenter mentions using Vim's system() function for interacting with the shell, while another discusses the use of :! for executing external commands.

  Finally, some comments offer alternative perspectives on automation in general. One commenter suggests that excessive automation can hinder learning and understanding, while another emphasizes the importance of carefully considering the costs and benefits of automation before implementing it. This highlights a common thread in the discussion: finding the right balance between automation and manual control for optimal efficiency and productivity.