as far as i can tell, the only difference between the specifications for compactflash type 1 and type 2 is that type 1 cards measure 3.3mm in thickness, and type 2 cards measure 5.0mm in thickness. Both types are 50 pin edge connectors, and have same operational specifications. the only difference i know of is the physical sixe (thickness). in general, this allows type 2 cards to has higher capacity, and type 1 cards should work in a type 2 slot, but not the other way around obviously because of the size difference. type 1 cards have capacities up to 512 megs (and possible 1 gig even) commercially available. Type 2 cards allow for more options, including the ibm microdrive system.