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PostPosted: Sun Jan 24, 2021 12:17 pm 
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This might be of interest - it's portable, by intent, rather than being 6502 specific.

Here's documentation in PDF format. Here's a home page.

Although the central VM is written in C, I see it's buildable with TinyCC, and there's a barebones version, so I hope it's not too large for our world. In any case, perhaps there are some nice ideas within which can be borrowed.

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RETRO is a clean, elegant, and pragmatic dialect of Forth. It provides a simple alternative for those willing to make a break from legacy systems.

The language draws influences from many sources including traditional Forth systems, cmForth, colorForth, Factor, and Parable. It was designed to be easy to grasp and adapt to specific uses.

The basic language is very portable. It runs on a tiny virtual machine (Nga), which is written in C. There are multiple interface options, the main one (rre) is buildable with just the standard C compiler and libraries on most systems.


(via here and here)


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PostPosted: Mon Nov 07, 2022 4:27 pm 
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FYI: The link to the PDF above is broken.

I wanted to read it because I am curious why the authors wrote this Forth. Especially because writing the VM in C is a bit of a bold choice for a Forth interpreter.


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PostPosted: Mon Nov 07, 2022 7:41 pm 
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There's a copy on the Internet Archive's Wayback Machine:
https://web.archive.org/web/20210124121 ... Manual.pdf


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PostPosted: Tue Nov 08, 2022 12:43 am 
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That was a good idea.

I downloaded it and started skimming it. So far it looks like it is less bare bones than the Forths I am used to. Specifically it includes namespaces, support for mixed data type arrays, and some string functions. Also, because it is built on top of the C RTL it can have access to C's floating point data types and functions.

Update: It also has a socket API, which shouldn't be a surprise given that it is written in C. But that would allow for network programming in Forth which might please some people.


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PostPosted: Wed Nov 09, 2022 8:53 pm 
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It's clear the authors wanted to target lower end hardware because their floating point library supports 64 bit to 32 bit compaction of floating point quantities. The idea is that it should reduce the memory footprint while only losing some precision.

Their compaction algorithm is pretty simple and they reference a paper on it. They store the square root of the number and square it to restore the number.


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