Milpitas, Calif.-

Cable-modem manufacturer Com21 Inc. is buying BitCom Inc., a privately held engineering-consulting firm based in Germantown, Md., for $4 million in cash.

BitCom-which specializes in wireless, satellite and networking engineering-will become Com21's Maryland Development Center.

The unit will initially focus on Com21's asynchronous-transfer-mode-based "Com-UNITY Access System," an end-to-end broadband-access system including headend and cable-modem equipment and network-management software.