Vintage (1976) Hewlett-Packard HP-25C Continuous Memory Programmable Scientific Calculator. Works when plugged in with adapter, holds a charge but I don't know for how long. I have not opened the battery compartment. All keys work. Includes HP-25C calculator, case, adapter, original paperwork - owner's manual handbook, applications programs book, quick reference guide, registration card, and original purchase invoice. Ships with original box which shows shelf wear. Wi...ll ship promptly. Serial number 1708S20718.