The Telmex CDROM controller connects to the PCMCIA port of the A600 and A1200. It consists of a PCMCIA card, and external CDROM case housing the CDROM and two PCBs and a is powered by a 13.5v power supply. The case also has sterieo audio out and audio in connectors. The audio in is mixed with the audio from the CDROM. The PCBs step down the voltage to provide 5v and 12V to power the CDROM and audio mixing circuit. The cable between the CDROM unit and the PCMCIA is quite heavy duty and there's a driver for the unit in the IDE-Fix software suite. To get CDROMs working, it may be necessary to remove the "master" jumper.

Thanks to Sebastian