Marathon 3690J is a hardware system developed by IBM for use in retail and banking applications. It consists of a base system unit, one or two interchangeable processor units, power supplies, expansion drawers, and additional peripheral devices. The base system unit contains three main parts: a main circuit board, a processor, and a memory. It supports two IBM 3990 Series processor models, operates using IBM's MVS/XA operating system and has an external storage capacity of up to 8GB. Additional peripheral devices and drawers may be added for a total storage capacity of up to 16GB. It is engineered for data security and reliability, offering the latest encryption and authentication technology.