Casio MRG-1 / MRG-1B Manual — Module 1556

Two owner's manual PDFs for the Casio module 1556, each a different scan (English included). Casio fitted it in 4 models, including the MRG-1 and MRG-1B — the full list is below. Casio's spec sheet lists one CR2016, with 24 months of battery life and accuracy within ±15 seconds a month; the module first shipped in Jul 1996.