Casio BG-391 Manual — Module 1623

Nine owner's manual PDFs for the Casio module 1623, each a different scan (English included). Casio fitted it in the BG-391. Casio's spec sheet lists one SR1120W and a SR621W (for EL) backup cell, with 15 months of battery life and accuracy within ±15 seconds a month; the module first shipped in Jul 1997.