A system is provided for controlling, real-time logging, and archiving complex commercial transactions such as the purchase and financing of an automobile. An electronic contract disclosure unit or ECDU includes a digitizing display for imaging documents involved in the transaction and a digitizer for manual interaction with images on the display. A computer controls the transaction, and may for instance, control the order of presentation of documents to a vehicle purchaser, receive the purchaser's signature on the displayed documents when required, offer choices of various packages that can be accepted or declined by the purchaser, and insures that the entire transaction is carried out properly. The ECDU logs the transaction for future review and preferably records video and audio. Fingerprint readers allow participants to select between options by pressing their thumb or finger on the readers.