13. A smart card, comprising:

a microprocessor and associated memory; and

12. The transaction system of claim 6 wherein said user card is a smart card.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

11. The transaction system of claim 6 wherein one of said peripheral devices includes power supply terminals that are connectable to contacts of the user card to supply power to said microprocessor.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

10. The transaction system of claim 6 wherein said microprocessor selectively provides a data communication path between said two data input/output contacts to enable said first and second peripheral devices to communicate with each other or only with said user card.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

9. The transaction system of claim 8 wherein said operating protocol conforms to an ISO standard for smart cards.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

8. The transaction system of claim 6, wherein some of said plurality of contacts, including said first data input/output contact, comprise a predefined set of contacts associated with an operating protocol, and said second data input/output contact is not included within said predefined set of contacts.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

7. The transaction system of claim 6, wherein said first peripheral device further includes a clock terminal, that is connectable to one of the contacts of said user card.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

6. A user card transaction system, comprising:

a user card containing a microprocessor and associated memory, and a plurality of contacts for transferring data to and from said microprocessor and memory, including a first data input/output contact and a second data input/output contact;

5. The transaction system of claim 1 wherein said interface device includes a power supply that is connectable to contacts of the user card to supply power to said microprocessor.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)

4. The transaction system of claim 1 wherein said peripheral device includes power supply terminals that are connectable to contacts of the user card to supply power to said microprocessor.

United States Patent 6,199,128 Inventors: Sarat; Jean-Marc (Belmont, CA)