🚀 go-pugleaf

>> rather redirect all output to a memory location

Sounds like a virtual screen handling system to me. 
I don't know how you can handle it directly using printf...
but if you could somehow associate a file with a memory location
you could then reopen standard in as that memory location.. I don't
think you'll be able to handle this under ms-dos though.
 
WAIT A MINUET (musical interlude)
all your printf's could be #define'd to sprintf, but this
would still require modification to your printf calls (addition of 
the address argument)

#define'ing printf to another routine of your choice to do the 
printf to a memory location would work fine for printf, but
the rest of your I/O would be left on the screen..