"Apple iBook G3 700MHz" has 2 (1 not upgradeable) Memory Slots. Each slot has a max memory limit of 640MB (up to 512MB in user accessible slot)GB which gives a combined max memory of 640MB (up to 512MB in user accessible slot) for the machine. You can simply add extra module of rams up to 640MB (up to 512MB in user accessible slot)GB to the empty slot(s) or replace your current one with the higher sized modules. We recommend ordering as matched pair to achieve dual channel speed (twice faster on the same frequency). We always send matched pairs for quantities more than one.