Casio DW-002S / DW-002US Manual — Module 1557

Two owner's manual PDFs for the Casio module 1557, each a different scan (English included). Casio fitted it in 4 models, including the DW-002S and DW-002US — the full list is below. Casio's spec sheet lists one CR2016, with 2 years of battery life and accuracy within ±15 seconds a month; the module first shipped in May 1996.