Complex sentence: The 2610 and 2650 models were supplied with maps on CD plus a 128MB CF card, while the 2620 and 2660 models had no CDs, because maps were pre-installed on the 2.2GB Microdrive.
Split into simpler sentences: The 2610 and 2650 models were supplied with maps on a CD plus a 128MB CF card. The 2620 and 2660 models did not come with a CD and the maps were pre-installed on the 2.2GB Microdrive.