Anyone know how the RamFactor bank select works?

[BLuRry <brendan.robert@gmail.com>]

So I'm getting closer to RamFactor emulation, but this time instead of trapping all the calls to the card I just use the RamFactor rom image.  I noticed that the file has a two copies of the rom back-to-back.  Is there any significance to this?

Observation: On boot, the bank select (I/O register 15) of RamFactor is set to zero.  However, when I try to initialize the card and call its firmware (pr#5), I get a crash.  I logged that calling pr#5 sets the firmware select register to 255 and then 254 before it hangs.

Also subsequent attempts to access the ram card decrements the firmware select value by 22 every time.  In Prodos, for example, this results in an I/O ERROR on the screen after it tries selecting a lower firmware bank again.

But the manual doesn't explain what the bank select is for, just that it's there.  Does anyone know what this register is for or have an idea of how it might work?  

Does the RamFactor have the ability to set up its own AUX bank ram even though it's in a regular slot?

Many thanks in advance!
-Brendan