TS1990A iButton Memory In a sense, all iButtons are memory buttons because there are no iButtons without memory. Therefore, the concept of a mobile memory chip that communicates by touch remains fundamental to all iButtons. As the iButton family has grown, however, memory only iButtons are now distinguished from iButtons with extended capabilities such as a microprocessor, clock, and/or environmental sensors. Memory iButtons come in these different types to allow you to pick the right device for your specific application. All memory iButtons have these characteristics: Unique and unalterable factory-lasered address Low-cost, low-power 1-Wire? interface Ability to operate as mobile database, in either standalone or networked application designs Memory iButtons can be divided into the following different categories: The Address Only iButton is our TS1990A and is our basis model. It contains 64bits of Read Only Memory (ROM) and is used in many different applications such as: Access Control as a Key Route Compliance as a Location Identifier Inspection and Maintenance for Equipment Identification TS1990A is compatibale with DS1990A-F3/F5 completely.Because TS1990A also use DS2401 chip that DS1990A uses.