lbForth Lite

This is a Forth cross compiler for tiny devices. It's based on lbForth. Supported targets are 8051, AVR, Cortex-M, MSP430, PIC, and STM8. There's also support for some classic machines: 6502 and PDP-8.

This is a temporary battleground to get things up and running. I expect to fold the finished result back into lbForth.

The targets are tested using these simulators: naken_asm, uCsim, simulavr, gpsim, simh, and thumbulator. The status of the tests is:

The compiler is suitable for parts with 1K program memory and 64 bytes RAM. The kernel code occupies 100-500 bytes, and it's recommended to reserve about 24 bytes for the stacks. At this size, only a bare minimum of Forth words are supported. All targets come with a prefix assembler with its own unique syntax.

There is no resident interpreter or compiler in the target. Things are set up to provide target interaction through tethered operation, but it's not implemented yet. For now, the output is a flat binary file. ELF or Intel hex format can be made available on request.

The assemblers, compiler, and kernel are written in Forth and are all very simple. The user is encouraged to make modifications as see fit.

Manual

See here.

Glossary

Compile-time words:

: ; [ ] CONSTANT VARIABLE CODE END-CODE
['] [CHAR] LITERAL
IF THEN ELSE AHEAD BEGIN AGAIN UNTIL WHILE REPEAT

Run-time words:

COLD WARM
! C! @ C@ +!
DROP NIP DUP ?DUP SWAP OVER
>R R> R@
+ - 2* 2/ INVERT NEGATE AND OR XOR 1+ 1- CELL+
0= 0< 0<> = <>