The RAM expansion modules used in the PowerBook G4 computer are standard 144-pin 8-byte DRAM SO-DIMMs, as defined in the JEDEC specifications.
The mechanical characteristics of the RAM expansion SO-DIMM are given in the JEDEC specification for the 144-pin 8-byte DRAM SO-DIMM. The specification number is JEDEC MO-190-C. To obtain a copy of the specification, see the references listed at "RAM Expansion Modules".
The specification defines SO-DIMMs with nominal heights of 1.0, 1.25, 1.5, and 2.0 inches. The PowerBook G4 computer can accommodate SO-DIMMS with heights of 1.25 inches or less.
ImportantThe PowerBook G4 computer will not accept a 1.5 or 2-inch SO-DIMM.
The JEDEC specification defines the maximum depth or thickness of an SO-DIMM as 3.8 mm. That specification is also a maximum: Modules that exceed the specified thickness can cause reliability problems.