Fairlight-CMI

Hello readers,

I've read about the technical differences between a II and IIx. But 
what does this mean in a studio? Does a II have limitations in 
sequencing or in the sample/soundlength. Does the operating system work 
for both machines? Is a series II upgradable to IIx? Do both machine 
have same stability?
I'm asking because I bought the II(x) on Ebay yesterday and know tere 
are doubts if this one is a IIx.
My second question is, does anybody have a technical schedule of a 
lightpen or foto's of the inside electronics, maybe the original 
company who manufactured these pens?

Thanks in advance/Hope you can help me out.

Hans
The Netherlands