ref #82

VE works! well, at this point, we can say that Collapse OS runs on
PC/AT. A little cleanup and docs writing and we're done!

On real hardware, there aren't always 2 heads...

instead of hardcoded drive 0.

That INT 13H logic was a bit tricky to implement...

read-only for now.

Also, fix (roll) which wasn't properly implemented.

Forth intepreter now works! There's still DOES> and overflow checks
to implement, but otherwise, we have it!

Not working, but we do get that sweet "CollapseOS".

almost there!

This port is taking shape!

8086 asm is a lot terser than z80... Those indirect memory operations
are very handy.

find is the biggest chunk of logic of the boot code. The 8086 version
is significantly terser than the z80 one. REP/CMPS helps...

Not comparing strings yet. Without asm tooling support, it's a big
chunk to swallow at once. It's progressing well!

I'm not sure yet where I'm going, but I'm not going to build the
8086 port from the ground up like I did with the z80, that is,
making is sustain itself and eventually merge its forth code with
core words. That would be too much work which would then be thrown
out (all those words I'll initially have to implement in asm which
are already implemented in Forth).

What I *think* I can do is build a mirror version of z80 boot code
and cross-compile it from the z80. This means it has to follow z80
stable ABI.

Nope, I'm not sure where I'm going...

MBR code now strictly loads OS code into memory and jumps into it.

Now, I've got to consolidate my assembler code, modrm logic is
messed up.

All recipe makesfiles would previously assume a built emul/.

Fixes #113

Also, I've run VE on the TRS-80 for the first time! It doesn't work
well though. Screen is mostly blank all the time.

I removed instructions from the recipe which became obsolete when
Collapse OS became 100% bootstrapped. Also, I've updated instructions
to change the NL override which is necessary for blkup to work.

Now that adev is directly in core, things are easier.

The keyboard is a bit glitchy, but these are the same glitch as those
that were already present in Z80 Collapse OS. They still need fixing...

AGAIN, becomes a shortcut for "' RJMP AGAIN?,"

I decided to keep SKIP, .. TO, (renamed from AT,) around and limit
IF, .. THEN, to the simple BRNE case.

Will change to IF, .. THEN, but I need a way to easily reverse a
BR op. But from this commit, the translation of sms/kbd/ps2ctl.asm
is complete! perfect binary match!

Still making great progress on sms/kbd/ps2ctl. Still matching ref
binary.

next step: implement ST.

Getting good! still advancing on ps2ctl in sms/kbd and still
matching reference binary.

This will make it easier to fit BR* in there.

Still binary matching. Next step is branching support.

So far, the resulting binary matches.

and renamed it "Core words". Also, reworded the presentation.

More portable