This commit adds ?DUP IF guards to MOVE and MOVE- that make them exit
when u is 0. Without these guards a DO loop was executed 65535 times
instead of 0.
In particular, this fixes a crash when "105 LOAD I " is executed
immediately after boot. Block editor word "I" passes IBUF length (0)
to MOVE- and MOVE in this case, causing a crash.
(well, not PC@ and PC!, but I'm not even sure what would be the role
of these in a PC/AT. they're only used in drivers on the z80 front,
so they will not be immediately needed. todo... )
Now comes the fitting part.
Instead of having wordref point to core word routines, I made them
into word 4 word types. It liberates space into the stable ABI and
should make porting to other arches easier.
I'm also thinking of combining word type with the namelen field
for precious bytes saving, but not now...
It was useful when we still had the relinker, but now it has no use.
I was waiting a bit to see if the distinction would be useful again,
but it seems like it won't.
Documentation in block 100 says a number followed by a space or return
lists the contents of the block. However, typing any other character
does this too, because _pdacc returns -1 in this case.
This is annoying because typing "n" instead of "N" immediately after
jumping to some block was bringing you to block 0. Now "n" is ignored
instead.
This commit changes the condition for printing to explicitly check for
the value of 1, which means whitespace according to _pdacc documentation
in block 355.
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...
