\ Metacompilation process for ForthOS                                vandys
Metacompilation is the process of generating a new system image
while running under a different system.  The image being built
is for the "target"; the machine on which the compilation is run
is the "host".  Metacompilation permits the target to be independent
from the host; the target may not even be the same CPU type as
the host.

Metacompilation is achieved in three basic steps.  First, a very
basic system image is generated.  After generation, this image is
relocated to the appropriate address so it can run when loaded
on the target.

Second, the basic system image is loaded and run on the target.
This image provides a basic Forth system, but without editor,
assembler, debugger, and so forth.  Most notably, this system
does not have a filesystem available.  A set of basic words, followed
by the filesystem source, is loaded on top of the basic system.

With the filesystem now available, the third step is to load all
the various utilities out of the filesystem, things such as assembler,
debugger, disassembler, editor, and other things.



\                                                                    vandys
Once the system has been loaded up with all desired code,
the "unexec" word saves the image back out to disk.  One can
now boot back into the system in its fully loaded state.

On the following screen, the actual steps needed are listed.



















\ Building system image                                              vandys
On a system with at least the assembler loaded, execute:

10000 fs.cwd!    \ Return to root of filesystem
fs.cd kernel     \ Kernel source
fs.load mksys    \ Build basic system
\ Verify the stack arguments; the second is the block location.
\  This will generally be 1 for primary boot, or 100 for secondary.
write_image      \ Save image

\ (Now boot this image)
11202 11204 thru \ Load extra source
11828 11837 thru \  and load filesystem

\ Now load rest of source through filesystem
10000 fs.cwd!    \ Set root of filesystem
fs.cd src        \ Move to rest of source
fs.load mk       \ Load it in

1 (or 100) unexec         \ Save boot image