DOS partition with Unix

[James Choi]

I was told I can have only 30M hard disk dedicated to pure DOS if it wants
to co-exist with ISC Unix.  Is it true?
Can I have bigger DOS disk if I use a second physical hard disk?
Is the limitation similar under SCO Unix as well?

And is it true that ISC supports upto 16M of RAM only?

Is there a number I can call to ask ISC questions?  It has been over 30
days since I bought the product and I seem to be on my own in this
wonderland.

Any help will be greatly appreciated.
James Choi