Ultimax mode VIC II access to external RAM?

Ultimax mode is clearly one of the most confusing (and thus interesting) 
modes on the C64.

I see that one can populate external RAM on the cart bus, and access it 
in Ultimax mode.  But, the documents don't seem to indicate if the 
VIC-II an "see" that RAM in the mode.

http://codebase64.org/doku.php?id=base:memmanage

However, this is not true for the Ultimax video game
configuration. In that mode, the internal RAM ignores all
memory accesses outside the area $0000-$0FFF, unless they
are performed by the VIC, and you can write to external
memory at $1000-$CFFF and $E000-$FFFF, if any, without
changing the contents of the internal RAM.

Marko noted long ago that he was aware of a page the VIC could read 
from, and there is this note on the list archives from 1999:

http://cbm-hackers.2304266.n4.nabble.com/lt-Q-gt-C64-ULTIMAX-mode-td4059331.html

Does anyone have more information?

Also, on this portion of the archive:

http://cbm-hackers.2304266.n4.nabble.com/Ultimax-questions-td4615195.html

skoe notes that he was leery of just decoding the address lines because 
of the state of $01.  How would the state of $01 be of interest or 
concern in Ultimax mode?

Jim

-- 

Jim Brain
brain@jbrain.com
www.jbrain.com