Internal Design The motherboard PCA is the central component of the OmniBook design. It plays a role in virtually all system functions. The CPU module and most other subsystems connect to the motherboard. The following figure shows the connections among the replaceable electrical modules. As a substitute for a functional block diagram, see the table on page 1-13—it lists the roles that the replaceable modules play in each of the functional subsystems. Figure 1-6. Replaceable Module Diagram 1-12 Product Information HP OmniBook XE2