They are the one's that can be programmed and reconfigured the logic functions while on the system board which is suitable for faster prototyping.

它支持在系统编程，在系统重构器件的逻辑功能，很适合产品的样机开发。

youdao

To that end, Martijn, the UI designer, has dropped by Vimeo to provide us with a "sneak peek" at the device's operation, including some demos on iOS and a connected prototyping board, using a custom tool that sends designs to the Pebble screen from any graphics program in real-time (a feature that will reportedly also be available in the SDK).

ENGADGET: Pebble team posts UI preview, provides an early look at how you'll interact with the E-Paper Watch

Pre-soldered connectors and prototyping areas on each board make it easier to customize the robot platform with additional sensors and electronics.

ENGADGET