MilliForth-6502 is a minimalist Forth implementation for the 6502 processor, designed to be incredibly small while remaining a practical programming language. It features a 1 KB dictionary, a 256-byte parameter stack, and implements core Forth words including arithmetic, logic, stack manipulation, and I/O. Despite its size, MilliForth allows for defining new words and includes a simple interactive interpreter. Its compactness makes it suitable for resource-constrained 6502 systems, and the project provides source code and documentation for building and using it.
The author meticulously debugged a mysterious issue where transferring Apple DOS 3.3 system files to a blank diskette sometimes resulted in a bootable disk, and sometimes a non-bootable one, despite seemingly identical procedures. Through painstaking analysis of the DOS 3.3 source code and assembly-level debugging, they discovered the culprit: a timing-sensitive bug within the SYS.COM program related to how it handled track zero formatting. Specifically, SYS.COM occasionally failed to wait for the drive head to settle after seeking to track zero before writing, resulting in corrupted data on the disk. This timing issue was sensitive to drive mechanics and environmental factors, explaining the intermittent nature of the problem. The author's fix involved adding a small delay within SYS.COM to ensure the drive head had stabilized before writing, resolving the frustrating bug and guaranteeing consistent creation of bootable disks.
Several Hacker News commenters praised the author's clear and detailed write-up of the bug hunt, appreciating the methodical approach and the insights into early DOS development. Some shared their own experiences with similar bugs and debugging processes in other systems. One commenter pointed out the historical significance of relying on undocumented behavior, a common practice at the time due to limited documentation. Others discussed the challenges of working with older hardware and software, and the satisfaction of successfully solving such intricate problems. The overall sentiment reflects admiration for the detective work involved and nostalgia for the era of simpler, yet more opaque, computing.
The 6502 assembly language makes a great first foray into low-level programming due to its small, easily grasped instruction set and straightforward addressing modes. Its simplicity encourages understanding of fundamental concepts like registers, memory management, and instruction execution without overwhelming beginners. Coupled with readily available emulators and a rich history in iconic systems, the 6502 offers a practical and engaging learning experience that builds a solid foundation for exploring more complex architectures later on. Its limited register set forces a focus on memory operations, providing valuable insight into how CPUs interact with memory.
Hacker News users generally agreed that the 6502 is a good starting point for learning assembly language due to its small and simple instruction set, limited addressing modes, and readily available emulators and documentation. Several commenters shared personal anecdotes of their early programming experiences with the 6502, reinforcing its suitability for beginners. Some suggested alternative starting points like the Z80 or MIPS, citing their more "regular" instruction sets, but acknowledged the 6502's historical significance and accessibility. A few users also discussed the benefits of learning assembly language in general, emphasizing the foundational understanding it provides of computer architecture and low-level programming concepts. A minor thread debated the educational value of assembly in the modern era, but the prevailing sentiment remained positive towards the 6502 as an introductory assembly language.
The original BBC Micro Elite source code, written in 6502 assembly, has been released and extensively commented by its author, Ian Bell. This release provides a fascinating look into the technical ingenuity behind the classic space trading game, revealing how Bell managed to cram a complex universe simulation, including 3D wireframe graphics and combat, into the limited resources of the 8-bit machine. The heavily commented code offers valuable insights into the optimization techniques employed, such as clever use of lookup tables and bit manipulation, making it a great resource for those interested in retro game development and 6502 programming.
Hacker News users discuss the newly released and heavily commented source code for the 8-bit game Elite. Many express excitement and nostalgia, praising the code's clarity and the detailed comments which provide insights into the game's development process. Several commenters highlight the impressive feats accomplished on such limited hardware, like the use of clever algorithms for 3D graphics and procedural generation. Some discuss the historical significance of Elite and its influence on subsequent games. A few users share personal anecdotes about playing Elite in their youth, while others analyze specific coding techniques used. There's also discussion about the challenges of working with 6502 assembly and the ingenuity required to overcome hardware limitations. The overall sentiment is one of appreciation for the release of this historical artifact and the opportunity it provides to learn from the pioneers of game development.
This GitHub repository contains the fully documented and annotated source code for the classic game Elite, specifically the BBC Micro version adapted for the Commodore 64. The code, originally written in 6502 assembly language, has been meticulously commented and explained to make it easier to understand. The project aims to provide a comprehensive resource for anyone interested in learning about the game's inner workings, from 3D graphics and ship control to trading mechanics and mission generation. This includes explanations of the game's algorithms, data structures, and overall architecture. The repository also offers resources like a cross-reference and memory map, further aiding in comprehension.
Hacker News commenters on the Elite C64 source code release express enthusiasm and nostalgia for the game. Several discuss the ingenuity of the original developers in overcoming the C64's limitations, particularly its memory constraints and slow floating-point math. Commenters highlight the clever use of lookup tables, integer math, and bitwise operations to achieve impressive 3D graphics and gameplay. Some analyze specific code snippets, showcasing the elegant solutions employed. There's also discussion about the game's impact on the industry and its influence on subsequent space trading and combat simulations. A few users share personal anecdotes about playing Elite in their youth, emphasizing its groundbreaking nature at the time.
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https://news.ycombinator.com/item?id=43503897
Hacker News users discussed the practicality and minimalism of MilliForth, a Forth implementation for the 6502 processor. Some questioned its usefulness beyond educational purposes, citing limited memory and awkward programming style compared to assembly language. Others appreciated its cleverness and the challenge of creating such a compact system, viewing it as a testament to Forth's flexibility. Several comments highlighted the historical context of Forth on resource-constrained systems and drew parallels to other small language implementations. The maintainability of generated code and the debugging experience were also mentioned as potential drawbacks. A few commenters expressed interest in exploring MilliForth further and potentially using it for small embedded projects.
The Hacker News post for MilliForth-6502 has a modest number of comments, focusing primarily on its size, speed, and potential applications.
Several commenters express fascination with the extreme minimalism of MilliForth, marveling at how a functional Forth system can be implemented in such a small footprint. They discuss the challenges and ingenuity involved in fitting a complete language within such tight constraints. Some commenters delve into the technical details of its implementation, analyzing how certain features are achieved with limited resources.
A recurring theme is comparing MilliForth to other small language implementations, particularly FORTHs and BASICs on similar hardware. Commenters share anecdotes and experiences with historical systems, highlighting the tradeoffs between size, speed, and functionality. Some discuss how MilliForth's size compares favorably to other FORTHs on the 6502, while acknowledging that its minimalist nature may impact usability for larger projects.
The speed of MilliForth is also a point of discussion. Some commenters question its performance relative to other FORTHs and even assembly language, wondering if the extreme size optimization comes at the cost of execution speed. Others express interest in benchmarking MilliForth against similar systems to quantify its performance characteristics.
Regarding applications, some commenters speculate on potential uses for such a small FORTH, suggesting embedded systems, retrocomputing projects, and educational purposes as possible areas where MilliForth could be valuable. The idea of fitting a complete language within the limited memory of older hardware is particularly appealing to retrocomputing enthusiasts. One commenter mentions using a similar small FORTH on an Apple II, demonstrating the practicality of such systems.
Finally, a few comments focus on the readability and maintainability of the code. Due to its highly optimized nature, some commenters acknowledge that MilliForth might be challenging to understand and modify. However, the overall sentiment leans towards appreciation for the technical achievement, even if the code itself is not intended for extensive modification.