The G3 iBook has one memory socket and can be upgraded using a 128MB, 256MB or 512MB SDRAM module.

Standard Memory
128MB soldered on board
Maximum Memory
640MB
Memory Expansion (No. of sockets)
1 Expansion Socket
Memory Expansion
Install 1 at a time
Memory Sizes
128MB | 256MB | 512MB
Memory Speed (Type)
PC100