Determine the size of your PowerBook G4
The first step to distinguish which model of PowerBook G4 you own is to determine what size screen it has. PowerBook G4 computers are available in three screen sizes (measured diagonally): 12-inch, 15-inch, and 17-inch.

12-inch PowerBook G4 computers

PowerBook G4 (12-inch DVI), PowerBook G4 (12-inch 1.33GHz), and PowerBook G4 (12-inch 1.5GHz)

The PowerBook G4 (12-inch DVI) is distinguishable from the previous model by the DVI port on the side of the computer. The DVI port is the one outlined in red in Figure 1.

Figure 1 PowerBook G4 (12-inch DVI) DVI port

The PowerBook G4 (12-inch 1.33GHz) is physically indistinguishable from the PowerBook G4 (12-inch DVI) except for processor speed. The sticker inside the battery bay will give the processor speed of the computer.

The PowerBook G4 (12-inch 1.5GHz) is physically indistinguishable from the PowerBook G4 (12-inch DVI) and PowerBook G4 (12-inch 1.33GHz) except for processor speed. The sticker inside the battery bay will give the processor speed of the computer.