A personal portable terminal for financial transactions adapted for use with one or more data storage and transfer cards (DSTCs) and other external devices, such as point of sale terminals, is disclosed. The transaction device includes keyboard means for entering transaction data and control information, means for temporarily storing transaction data, and logic means for performing arithmetic, logical, and control operations. Said logic means further includes means for storing predetermined programs which are activated by instructions entered via said keyboard. Also included are display means for selectively displaying transaction data and means for transferring selected data from the transaction device into suitable storage means located in said other external device and into at least one DSTC. Further means are disclosed whereby account balance data in one DSTC may be credited while account balance data in another DSTC is debited as a result of the transaction.