Data logging and transfer system using portable and resident units

An electronic funds transfer system for enabling financial transactions to be carried out between either local or remote users, comprising a plurlaity of microprocessor controlled modules, each one of said modules including a housing carrying a display and a keyboard for manually entering funds transfer data, said housing containing microprocessor controlled circuitry including a memory, and a first optical interface coupled to the circuitry and extending through the housing to transfer electronic funds data bidirectionally with another one of said modules with said modules positioned adjacent each other with the first interfaces therof in optical registration, and a plurality of resident units, each one of said resident units including a housing having a receptacle to receive one of said portable modules and further having a second optical interface in said receptacle positioned to be in registration with one of said modules seated in said receptacle for bidirectional electronic funds data transfer with a module seated in said receptacle, said resident unit further including means for transferring data bidirectionally onto external communication lines, and data protocol means in each of said microprocessor controlled modules for automatically determining whether said each of said modules is (1) in direct communication with another of said modules via only said first optical interfaces thereof or in indirect communication via said first and second optical interfaces thereof with another of said modules through resident units in which said modules are seated or (2) in communication with a resident unit.