Originally posted by NickFitz
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When I implemented Forth (or FORTH if you insist) on the Atari ST I wrote the nucleus in assembler, including defining the word headers complete with link field and code field. Once I'd got that written I could then write the rest of the system and development environment in Forth itself. Then I implemented a Forth assembler (Reverse Polish 68000 assembly language FTW!) and rewrote the original assembler source in RP... and then it could assemble itself 
From that point on I could implement Forth anywhere else by first writing an assembler for the target processor, re-implementing a very small number of low-level words, and compiling a target image which I could then send to the target (via RS-232, naturally) and lo! it worked
Given that my implementation strategy was the same as that used by Chuck Moore (who invented the language), the nucleus actually included the OS - the only existing code it used was the firmware BIOS of whatever system it might be on. Other than that it did all its own disc handling and so on.
IIRC the ST nucleus - the absolute bare minimum of code to enable everything else to happen - came out to about 14K, although with the development environment loaded (including an editor and a debugger) it rose to the dizzy heights of about 22K
From that point on I could implement Forth anywhere else by first writing an assembler for the target processor, re-implementing a very small number of low-level words, and compiling a target image which I could then send to the target (via RS-232, naturally) and lo! it worked
Given that my implementation strategy was the same as that used by Chuck Moore (who invented the language), the nucleus actually included the OS - the only existing code it used was the firmware BIOS of whatever system it might be on. Other than that it did all its own disc handling and so on.
IIRC the ST nucleus - the absolute bare minimum of code to enable everything else to happen - came out to about 14K, although with the development environment loaded (including an editor and a debugger) it rose to the dizzy heights of about 22K
But they promised me! They said it was easy! 
And worst of all, they made out there would be something wrong with me if it didn't work first time. 
And of all the kinds of people in IT, the ones I really, really hate are those that patronise users. They damage the entire industry by thinking they are clever - when they are not. 
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