From: legalize+jeeves@mail.xmission.com   
      
   [Please do not mail me a copy of your followup]   
      
   Hi,   
      
   I have a slow-burn project to build an SBC around the Motorola 6805   
   CPU.  (Why?  Because someone gave me a pile of them.)  This CPU only   
   has 8K of address space.  I would like to have a ROM with FORTH in 4K   
   leaving ~3.5K of address space for user data/program.   
      
   The motivation for having FORTH in ROM was to have the SBC boot into   
   an interactive "ready to program" environment, kind of like how the   
   original IBM PC without floppy drives would boot into BASIC in ROM.   
      
   I dug around and found some FORTH implementations that seem like they   
   will do the job (e.g. fit in 4K) but examining the source code implies   
   that they will need some additional changes in order to execute from   
   ROM instead of RAM.   
      
   The 6805 has a tiny hardware stack (located in the zero page), so   
   FORTH's stack probably needs to be elsewhere?   
      
   The 6805 is also not the fastest CPU, so implementing as many of the   
   core words in assembly is probably best to get reasonable performance.   
      
   SBC project:    
      
   I found this ROMable FORTH for 8080/Z80:   
      
      
   Other repositories that are relevant to this project:   
      
      
   I have added these FORTH related files to the repo based on my   
   scouring of the inny-nets:   
      
      
   05EF21.ASM (6805 eForth 2.01, 3/17/99, C. H. Ting) looks promising,   
   but it assumes that the code space is writable and the first thing it   
   does is copy itself from ROM into RAM.   
      
   6805-4TH.TXT (RAFOS FORTH V1.0 26 March  1986) appears to be ROMable   
   ready, but didn't come with much documentation, so I'd have to spend   
   some time reverse engineering the assembly.   
      
   I'd love to hear if anyone has experience with these implementations   
   or suggestions for better implementations for my use case.   
      
   Thanks,   
      
   -- Richard   
      
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