BN-10 and BN-20 models
BN-20 running the main menu
Top and back sides
Connected to the optional serial cable. A PCMCIA memory card can be inserted in the opposite side.
Display card (top), its rear side is protected by a plastic cover,
main card and separate 1 or 2 MB memory card normally connected to the main card.
BN-40A, the 4 MB version with a better keyboard.
Picture taken from this Web site