Tweaking DOS.SYSTEM from Extra-K to support other DOS 3.3 variants

[Moll <MollyBaker@Spam.GMAIL.Spam.Spam.Spam.Com>]

I've been working on this concept, a DOS.SYSTEM that loads Pronto-DOS, 
or ZDOS, or TurboDOS, instead of DOS 3.3

I've gotten this far:

1. A program I wrote a few years ago to convert images of the running 
DOS to files and vice-versa.  It creates a file which needs only to have 
a 256-byte header, the first 256 bytes of DOS.SYSTEM, attached to it.

2. Found the format of DOS.SYSTEM and replaced the DOS image with ZDOS 
2.3 (DOS 3.3 variant).  File launches correctly with one exception: it 
immediately exits to BASIC after initialization, it does not attempt to 
RUN HELLO.

I'm still working on it but am open to input other than "you're wasting 
your time!" (I know I am, but still. XD)

Moll.