The original iBook (ones with the handle) all took the same RAM (PC66).

The Dual USB iBook series all takes PC100 SODIMMs regardless of the CPU speed. The lone exception of this is the original Dual USB 500 MHz iBook with only takes PC66 SODIMMs.

Starting with the iBook G4 was the transition to PC2100 DDR RAM. With the exception of the last G4 iBook Model, every iBook G4 takes PC2100 DDR RAM.

iBook

G3 Processor


300/350/400 MHz G3
PC66 SODIMM
Max RAM 576 MB


500 MHz G3 (Dual USB)
PC66 SODIMM
Max RAM 576/640 MB (depends on standard onboard RAM configuration)

500/600 MHz G3 (Late 2001)
PC100 SODIMM
Max RAM 640 MB

600 MHz G3 (14" Model)
PC100 SODIMM
Max RAM 640 MB

700 MHz G3 (16 MB VRAM 12"/14")
PC100 SODIMM
Max RAM 640 MB

700/800/900 MHz G3 (12"/14" Model)
PC100 SODIMM
Max RAM 640 MB

G4 Processor



800/933 MHz/1.0 GHz G4 (12"/14" Model)
PC2100 DDR SODIMM
Max RAM 1.12 GB

1.0/1.2 GHz G4 (Early 2004)
PC2100 DDR SODIMM
Max RAM 1.25 GB

1.2/1.33 GHz G4 (Late 2004)
PC2100 DDR SODIMM
Max RAM 1.25 GB

1.33/1.42 GHz G4 (Mid 2005)
PC2700 DDR SODIMM
Max RAM 1.25 GB