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portable VM for VolksForth

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Carsten Strotmann 2020-11-23 19:39:14 +01:00
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#+Title: Portable VM for VolksForth
#+Author: Carsten Strotmann
#+Date: <2020-11-23 Mon>
* Goal
* create a portable VM to run VolksForth
* multiple implementations (C, Go, Pascal ...)
* 64KB Memory + Banked extension memory
* Stack machine CPU (Data-Stack, Return-Stack)
* Stacks mapped into main memory
* Stack-Pointer as memory mapped register
* Implementation Idea
* 16bit alignment
* 16bit opcodes
* opcodes $0000-$00FF -> Forth primitives (dup, swap, drop ...)
* opcodes $FF00-$FFFF -> extended opcodes
* opcodes $0100-$FEFF -> implicit jump to subroutine
- allows easy implementation of ITC and DTC Forth
* memory $FFF0-$FFFF -> memory mapped I/O, Bankswitching etc