The mobile daughter card, also known as an MDC or CDC (communications daughter card), is a notebook version of the AMR slot on the motherboard of a desktop computer. It is designed to interface with special Ethernet (EDC), modem (MDC) or bluetooth (BDC) cards.
In 1999, Intel published a specification for mobile audio/modem daughter cards. The document defines a standard connector (AMP* 3-179397-0), mechanical elements including several form factors, and electrical interface. The 30-pin connector carries power, several audio channels and AC-Link serial data. Up to two AC'97 codecs are supported on such a card.
Several form factors are specified:
| 1 | MONO_OUT/PC_BEEP | AUDIO_PWRDN | 2 | |
| 3 | GND | MONO_PHONE | 4 | |
| 5 | AUXA_RIGHT | RESERVED | 6 | |
| 7 | AUXA_LEFT | GND | 8 | |
| 9 | CD_GND | 5 Vmain | 10 | |
| 11 | CD_RIGHT | RESERVED | 12 | |
| 13 | CD_LEFT | RESERVED | 14 | |
| 15 | GND | PRIMARY_DN | 16 | |
| 17 | 3.3Vaux/dual | 5VD | 18 | |
| 19 | GND | GND | 20 | |
| 21 | 3.3 Vmain | AC97_SYNC | 22 | |
| 23 | AC97_SDATA_OUT | AC97_SDATA_INB | 24 | |
| 25 | AC97_RESET# | AC97_SDATA_INA | 26 | |
| 27 | GND | GND | 28 | |
| 29 | AC97_MSTRCLK | AC97_BITCLK | 30 |