In industrial automation (like Fanuc, Siemens, or Allen-Bradley systems), these files are sometimes generated during the initial machine calibration. If lost, they cannot be simply downloaded from the internet; they must be re-generated by a technician or restored from a specific "System Image" backup created during the machine's commissioning. Conclusion
If you are trying to run games like Street Fighter EX2 Plus (Japan) or other ZN-1/ZN-2 titles, MAME checks for this file as part of the machine's required startup sequence. Because it is often missing or undumped, the emulator will report a and refuse to launch the game. Potential Solutions 78081g503.ic655 not found
Open cds.lib from your run directory. Look for a line like: In industrial automation (like Fanuc