OpenAI reported that its GPT-6.1 Sol model achieved 87 percent behavior preservation accuracy migrating COBOL code at low reasoning effort, rising to 98 percent at higher reasoning. The company said models can translate legacy COBOL, Fortran, and other languages into C++, Java, Kotlin, Python, and Rust without changing behavior. IBM estimates COBOL underpins over 40 percent of online banking systems and handles 95 percent of ATM transactions. Experts cautioned that replacing critical legacy systems remains unsolved.
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