How about this document. Its a quick overview of every thing you need to know abt the ISRs.
See attached.
Also I would recommend CCO q&a on ISR series. Its a great resource to understand the ISR series architecture.
Cisco used to have a training course called IMCR which gives an overview of all Cisco routers from SOHO to high end routers like 7200. I am not sure if they have that course any more or even updated content for the ISRs.
HTH
PS: please remember to rate posts!
Sankar Nair
UC Solutions Architect
Pacific Northwest | CDW
CCIE Collaboration #17135 Emeritus