gforth VS zeptoforth

Compare gforth vs zeptoforth and see what are their differences.


Gforth mirror on GitHub (original is on Savannah) (by forthy42)


A not-so-small forth for Cortex-M (by tabemann)
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gforth zeptoforth
3 5
109 48
- -
9.7 9.4
18 days ago 5 days ago
Forth Forth
GNU General Public License v3.0 or later MIT License
The number of mentions indicates the total number of mentions that we've tracked plus the number of user suggested alternatives.
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.


Posts with mentions or reviews of gforth. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2022-02-04.


Posts with mentions or reviews of zeptoforth. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2021-10-17.
  • Modules in zeptoforth
    1 project | | 9 Dec 2021
    I initially implemented a rather Forth 2012-like wordlist system based on GET-ORDER, SET-ORDER, GET-CURRENT, SET-CURRENT, and WORDLIST for my Cortex-M Forth, zeptoforth. However, I ended up finding these quite cumbersome and error-prone to use in code that makes heavy use of wordlists to control the namespace, as is the case with zeptoforth. As a result I decided to completely remodel wordlists into a module system which, while internally based on those five words, is outwardly much more like the module systems found in other languages.
  • Multicore multitasking for the RP2040 with zeptoforth
    1 project | | 21 Nov 2021
    Multicore support for the RP2040 with zeptoforth has been in the works for a while but up until the last few days has not been mature enough for me to even consider including it in the devel branch of zeptoforth. However, now it has reached the point where I can run multiple tasks simultaneously on separate cores. I have a working test that blinks the LED on the Raspberry Pi Pico at two different rates in two different tasks, one on each core, while simultaneously writing an asterisk to the console once every second from the second core and having a usable REPL in the main task on the first core. It should be noted that even the Micropython does not do this, as it only allows two tasks, one per core, rather than allowing multiple tasks to run on each core separately.
  • which forth do you guys use for normal day to day scripting and programming
    6 projects | | 17 Oct 2021
    I am the developer of zeptoforth, which is the main Forth I am using at the present. It supports the RP2040 (particularly the Raspberry Pi Pico, but it should work on other RP2040 boards), which I have been working with lately, and the STM32F407, STM32L476, and STM32F746 DISCOVERY boards. Note that it is not a desktop Forth; for that I would probably just recommend gforth.
  • zeptoforth 0.21.0 is out, now with RP2040 support!
    1 project | | 10 Oct 2021
    zeptoforth 0.21.0 ( is now out, and introduces support for the RP2040 microcontroller (e.g. Raspberry Pi Pico, any RP2040 board with Winbond Quad SPI flash should work). Note that it comes in UF2 format, so one codes not need to solder pins for SWD onto one's Raspberry Pi Pico format to load it, and also the Makefile automatically generates UF2 files. Furthermore, when said UF2 file is first loaded, it erases flash above it up to the 1 MB mark, so one does not need to use OpenOCD (with SWD) or a special eraser UF2 file to clear old code out of flash.
  • Why Forth?
    1 project | | 24 Mar 2021
    The result of this is zeptoforth, which I have been developing for about a year and four months. One could say that it fits the same niche as Mecrisp-Stellaris, and it admittedly supports far fewer MCU's at the present. I could have just used that rather than bothered to implement my own Cortex-M Forth, but I wanted to create my own Forth environment which I could play with as I saw fit (e.g. adding preemptive multitasking and other multitasking supports such as locks and channels).

What are some alternatives?

When comparing gforth and zeptoforth you can also consider the following projects:

durexforth - Modern C64 Forth

elfort - A Forth metacompiler that directly emits an executable binary for x86-64 Linux written in Arkam

swapforth - Swapforth is a cross-platform ANS Forth

r3d4 - r3 programing language for 64 bits Windows/Linux/Mac/Rasberry Pi 4

miniforth - A bootsector FORTH

r3 - r3 programing language