Casio CA-50 / CA-501 Manual — Module 437

Five owner's manual PDFs for the Casio module 437, each a different scan (English included). Casio fitted it in 9 models, including the CA-50 and CA-501 — the full list is below. Casio's spec sheet lists one CR2016, with 5 years of battery life and accuracy within ±15 seconds a month; the module first shipped in May 1984.