MyForth on Arduino Hardware Charley Shattuck MyForth is a method for building a target compiled tethered Forth for micro-controllers. It is an experiment in simplicity. Being “my” Forth, it is designed to be used in Linux. It is not an ANSI Forth. It is somewhat similar to arrayForth.

What is Forth? 1. Simple Virtual Machine or actual machine in some cases 2. Two Stacks RPN, no addressing modes 3. Essentially No Syntax words are parsed via whitespace and executed or compiled

What's Special about MyForth? 1. Target Compiled only object code needs to go to the target, compiler remains on host 2. Begins with an AVR Assembler Forth virtual machine is subroutine threaded custom “high level” words taylored to AVR instruction set 3. Based more on colorForth than ANSI Forth conditionals don't pop stack for,next rather than do,loop 4. Efficient Tail Recursion via ;

Pre-existing software... VIM, Gforth, AVRdude, Minicom VIM, editor with custom syntax coloring Gforth is the host Forth compiler Scripts 'c', 't' AVRdude is the Arduino bootloader Script 'd' Minicom is used to interactively test Script 'm'

Components Simple target compiler/assembler Decompiler/disassembler Macros (inline compilation) Primitives (macros and subroutines) Standalone interpreter Scripts (c, t, d, m)

Target Compiler

Decompiler Disassembler

Macros (in-line assembly)

Primitives (subroutines)

Sample Application