CDC slot

From ThinkWiki
Revision as of 19:15, 22 November 2019 by Bugmenot2 (Talk | contribs) (added measurements)
Jump to: navigation, search

The Communications Daughter Card slot in IBM literature or Modem Daughter Card slot (MDC) in Intel's standards, is an internal expansion slot found in older ThinkPads. Much like the MiniPCI slot, it is generally used as the 'mobile' variant of the Audio/Modem riser expansion slot.

Please note that all AC'97 ThinkPads with a CDC slot, utilize the Hirose DF12(5.0)-40DP-0.5V(86) connector, which is not compliant with Intel's MDC standard (specifies a TE Connectivity 3-179397-0 connector). The reason for violating the standard is unknown, but it is likely to be along the lines of IBM locking-in its customers to disallow purchasing identical CDCs from other competing manufacturers.

On the other hand, all HD Audio ThinkPads with a CDC slot utilize an unknown 18-pin ACES connector. This connector was also used by other competing manufacturers, which may allow the usage of their CDCs in a HD Audio ThinkPad. However, this might trigger an 'Invalid Daughter Card' error.


Certain CDCs may not work in certain ThinkPads, even if they are using the same connector. This is due to a different electrical pin-out, which varies among ThinkPads. Some might even reject a CDC by displaying an 'Error 1803: Invalid Daughter Card' message.

In some cases, a CDC from a newer ThinkPad may work in an older ThinkPad, although with limited functionality. Such a case exists, as an R32 using a BMDC taken from an R40 worked with no issue. It was not able to activate its Bluetooth functionality however, due to the said electrical pin-out difference.

List of available Communication Daughter Cards

See also

Photos (click to see full size)
CDC in a ThinkPad T43-2686
analog modem 56k at cdc

Models featuring this technology