An interface for a small form factor electronic device by enabling explicit measurement of extension or retraction of a retractable cord by monitoring the amount of string that passes by sensors, as the string exits the enclosure of the device. Input to such small form factor devices may be provided by sensors that measure the length of a string or wire that has been pulled out of an enclosure, in addition to an angle or direction (e.g., in 1-, 2- or 3-dimensions) at which the string was pulled out. Additionally, the rate of acceleration for the pulling and retracting motion may also be used as additional forms of input. In a further embodiment, a string interface is provided for a small form factor device that communicates information in the form of a pixel display provided integral with the string in response to string manipulation.