I was stumped for a while by a yarn puzzle: I could use DOS viewers such as
(the editor) elvis or viewhtml to read mail formatted in html, so long
as I saved the mail as separate files and ran the viewers
on these files, outside of yarn. However, if I tried to view the same
html text within yarn, the same DOS viewers failed.
For the editor elvis, I usually was told (I think by Pmode),
something like, ``not enough memory to hold environment.'' For
the viewer, vh.exe (viewhtml), I got a message (I know not from which
software) to the effect, ``Memory error at address B700.''
I recently solved the puzzle. If one escapes to DOS (with the !
command) from within yarnx.exe and runs mem, one learns that, in DOS's
view, yarnx is loaded in ``low'', conventional memory -- consuming
actually almost half of it. Of course, yarnx doesnt care because its
dos extender lets it use all the ram it needs.
But, it appears some of the other programs may care -- programs that
one runs while running yarn, for example editors, image viewers, text
decoders, signature handlers, etc. etc. Most of these are conventional
16 bit programs that have their own ideas about what kinds of memory
they need to do what. They seem to care what part of memory yarns gets
Turns out, it makes some kind of difference to other
programs, if you load yarnx high with ``lh yarnx.exe''. In this case,
mem reports that yarn resides in ``upper memory blocks'' rather than low
memory, when you shell out. Specifically, when I load yarnx high, low
and behold, my two html viewers happily format and display html text,
within yarn, with no error messages like the above.
Suffice it to say that loading yarnx high may enable some helper programs
to work inside yarn, that only brought error messages and frustration
There may be ways to achieve the same effect by twiddling with the
pmode memory setup paramaters, but I dont know enough about memory
allocation to do that. Hope this tip helps some poor soul.
One final, off topic tip: A DOS html viewer may also fail inside yarn,
because it only knows that a file is html text, if its filename has the
suffix, htm. This is true for elvis. However, metamail, at least, is smart
enough to call the viewer you specify, but not smart enough to create
a tmp file with the appropriate suffix. Instead, it creates random filenames
that will confuse any reader that is looking for clues in filnames.