Released September 8, 1998, AMR, short for audio/modem riser, allows OEMs to make one card with the functionality of either a Modem or audio or both as one card. This specification allows a motherboard to be manufactured at a lower cost and free up industry standard expansion slots in the system for other additional plug-in peripherals.
With portable computers, this slot was called the MDC (mobile daughter card).
With modems and sound cards being integrated into the motherboard, more people using broadband, and better technologies like PCIe (PCI Express), AMR never gained mass adoption. Today, AMR is no longer found or used with any modern motherboard.