512MB SDRAM in PowerBook and iBook?

The memory Tech Specs for the PowerBook G4 state: "128MB or 256MB of PC100 SDRAM; two SO-DIMM slots support up to 1GB." But how can you get up to 1GB with two slots and a maximum of 256MB per slot? Can you use 512MB RAM or not?

The memory Tech Specs for the new iBook state: "64MB of PC100 SDRAM, expandable to 576MB; or 128MB of PC100 SDRAM expandable to 640MB; single 1.25-inch standard SO-DIMM slot supports up to 512MB SO-DIMM." This more clearly implies that 512MB RAM is okay. But readers inform us that there may still be "specification" problems with the currently available RAM.

Update: Rob Simons writes: "I've been using two 512MB DIMMs from Transintl.com in my G4 PowerBook for almost two months now without any problems."

Others confirm that, although the "specs" wording may be a bit confusing, using 512MB RAM - from a reputable dealer - should work fine.