Internal Design The motherboard PCA is the central component of the notebook’s 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 notebook’s replaceable electronic modules. Table 1-9 on page 1-15 lists the roles that these modules play in the notebook’s functional subsystems. Figure 1-5. Replaceable Module Diagram 1-14 Product Information HP Omnibook XE4100/XE4500