Fanuc FROM/SRAM module for 0i-B/ 0i Mate-B/ 0i-C/ 0i Mate-C/ 16i/ 18i/ 21i A20B-3900-0163

📌 FANUC A20B‑3900‑0163 — FROM + SRAM Memory Module

Description:
The FANUC A20B‑3900‑0163 is a combined FROM (Flash ROM) and SRAM memory module used in FANUC CNC controllers. It provides both non‑volatile program storage and working memory required by the control system’s CPU and operating software.

Memory Configuration:

• 📦 32 MB FROM (Flash ROM) — stores the CNC controller’s firmware, system files, and program code.

• 💾 1 MB SRAM — acts as volatile working memory for system operation and data buffering, often battery‑backed for parameter retention during power loss.

Function & Role:
This memory card plugs into the main control board or backplane of compatible FANUC CNC systems (e.g., Series 16i, 18i, 21i Model A/B controllers) and serves as the central storage medium for the operating software and dynamic data that the CNC uses at runtime.

Typical Use:

• Firmware Storage: Holds the controller’s operating system and system programs that enable CNC functionality.

• Runtime Memory: The SRAM portion stores active data, ladder logic, and working parameters while the system is running.

• Replacement/Upgrade: Used when upgrading memory capacity or replacing a failed memory module in older controllers.

• Backups: After replacement, system programs and parameters may need to be reloaded from backup to match the specific machine configuration.