Moving Forth - Internals and TTL Processor

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In 2018 we have 50 Years of Forth. When I looked for a new project for an eBook I realized that one area is not very well covered:
How do the Forth internals work?
How can you build a Minimal Processor executing Forth directly?
How do you write an Assembler in Forth?
When I looked around for some documentation, I remembered this series of articles again. They seems to fit very well together.
I contacted Brad and asked for permission to publish them as part of the Forth Bookshelf.
He liked the idea so I started formatting. I did not change any of the original material.The only part I added was an appendix, where I redid some of the pictures, so I could understand them better.
As in many cases, additional material can be found on the Forth-eV.de Wiki, and we will start with the appendix added here, and what else we might come up.
I have to thank Brad Ridriguez for the copyright to publish this documentation.
Enjoy reading and any feedback please send to [email protected].

From Brad: Everyone in the Forth community talks about how easy it is to port Forth to a new CPU. But like many "easy" and "obvious" tasks, not much is written on how to do it! So, when Bill Kibler suggested this topic for an article, I decided to break with the great oral tradition of Forthwrights, and document the process in black and white.
Over the course of these articles I will develop Forths for the 6809, 8051, and Z80. I'm doing the 6809 to illustrate an easy and conventional Forth model; plus, I've already published a 6809 assembler [ROD91,ROD92], and I'll be needing a 6809 Forth for future TCJ projects. I'm doing the 8051 Forth for a University project, but it also illustrates some rather different design decisions. The Z80 Forth is for all the CP/M readers of TCJ, and for some friends with TRS-80s gathering dust.