12 megs of ram missing?

[T3000]

Heya,
Recently installed a FastLane ZIII w/64mgs ram into 3000Tower/3640 with 16mg of zip ram. Workbench shows 69.5mgs fast and about 1.9 chip. Show Config reads 16 fast, 52 fast, 2 chip. The numbers somehow don't add up. Shouldn't there be 80 fast? There is about 12mgs missing. :-o   I really don't want to pull the zip chips.

Any suggestions.    

...and no, the extra zips won't be up for grabs either. I have an extra 3000D that is in need of some more ram.
Thanks.

[T3000]

Thanks for the direction. Was gonna look there first, but can't read German.  The illustrations showed me the way. 81 megs total fast ram. Now I need to get Buster-11 and a couple other chip updates to use the scsi controller.