HP LaserJet 8150 memory help

I have some questions about memory requirements for HP LaserJet 8150s
and I'm kind of confused. I'm hoping that someone here can help me
out.

I recently acquired an 8150 (well, an 8150 formater board which I
stuffed in my 8100 to speed it up). Unfortunately, it only came with
40MB of total memory (config page top of right column). I'd like to
add more memory, because i have it from the 8100.
Now the 8150 DIMM slots (config page left column) says:

Dimm Slot 1: 8 MB Rom (I assume this is the EEProm or something like
this)
Dimm Slot 2: 32 MB SDRAM
Dimm Slot 3: 4 MB Flash
8 MB SDRAM
Dimm Slot 4: Empty

From a couple of sources (Kingston Memory WebPage and HP 8150 Service
Manual) it says that the memory at J10 (Dimm Slot 2) can't be removed
and / or upgraded.

1) Is it really true that I can't stick a 64MB SDRAM in Dimm Slot 2 /
J10?

2) All the of the 8150's I've seen (including at work) have this weird
4 MB Flash / 8 MB SDRAM chip. What is that? Can it be removed and
replace with a 32 MB or 64 MB SDRAM? Do I lose any functionality by
doing that?

If it matters any, I'm using something like Kingston KTH4100/32 and
KTH4100/64.

From the Kingston page it would seem that you can go to 160MB (32 + 64
+ 64) in an 8150, but I'm curious / confused why you can't go to
192MB as you can in an 8100 and whether I lose any functionality by
replacing the 4 MB Flash + 8 MB SDRAM in Dimm Slot 3.

Thanks.