An interfacing system facilitating user-friendly connectivity in a selected operating mode between a host computer system and a flash memory card. The interfacing system includes an interface device and a flash memory card. The interfacing system features significantly expanded operating mode detection capability within the flash memory card and marked reduction in the incorrect detection of the operating mode. The interface device includes a first end for coupling to the host computer and a second end for coupling to the flash memory card, while supporting communication in the selected operating mode which is also supported by the host computer system. The flash memory card utilizes a fifty pin connection to interface with the host computer system through the interface device. The fifty pin connection of the flash memory card can be used with different interface devices in a variety of configurations such as a universal serial mode, PCMCIA mode, and ATA IDE mode. Each of these modes of operation require different protocols. Upon initialization with the interface device, the flash memory card automatically detects the selected operating mode of the interface device and configures itself to operate with the selected operating mode. The operating mode detection is accomplished by sensing unencoded signals and encoded signals. The encoded signals are encoded with a finite set of predetermined codes. Each predetermined code uniquely identifies a particular operating mode.