Build Forth virtual machine / kernel

[znmeb]

Tentative architecture

• subroutine-threaded
• add :macro capability
• core is M0+ macro-assembler implemented in assembler with no 64-bit multiply
• need C and C++ library calls
• use eForth slow code in core
• use eForth register allocations
• search order wordset in core
• 16 bit integer and fractional arithmetic in core
• floating point stack in VM
• case insensitive, lower case used in all source code

[znmeb]

Brainstorming:

1. Write outer and inner interpreters top-down in macro-assembler. Use the Irreducible Complexity run-time setup as a guide.
2. Research porting ueforth.
3. Use bootrom FP stack in core
4. Consider a 16-bit Forth VM - leaves lots of RAM for a BLOCK filesystem and buffers

[znmeb]

Done - adopting zeptoforth as base