Borland C++ 2.0 compiler source reconstructed from binaries by reverse-engineering effort

The complete source code for Borland C++ 2.0, the professional IDE and compiler suite released in 1991, has been reconstructed from its original binaries by a developer known as Abedegno. The resulting source produces byte-identical output when compiled, matching the original toolchain exactly. This was accomplished using Exhume, a Claude Code-based automated reverse-engineering tool developed specifically for this effort, with the full methodology documented separately.

The reconstructed source is particularly relevant for preservation of DOS-era software, historical compiler research, and understanding pre-standardization C and C++ implementation details. Borland C++ 2.0 predated both the C89 standard's widespread adoption and the C++98 standard by several years, making it a significant artifact of early commercial compiler development.

Reconstruction methodology and technical significance

• Exhume tool: The reconstruction employed a custom tool called Exhume, built on Claude Code, to automate the decompilation and source generation process from original Borland C++ 2.0 binaries.
• Byte-perfect verification: The claimed output is verified as byte-perfect, meaning binaries produced by recompiling the reconstructed source are identical to the original shipped toolchain binaries.
• Pre-standardization codebase: The compiler predates formal C++ standardization, implementing the language as it existed in 1991, several years before the C++98 ISO standard.
• DOS-era toolchain context: The reconstructed source preserves a commercial compiler from the period when C had only recently been standardized as C89 and x86 DOS development dominated professional software engineering.

Why it matters

This reconstruction contributes to open-source software preservation efforts by making a historically significant commercial compiler inspectable and modifiable for the first time. For retrocomputing enthusiasts, DOS preservation projects, and researchers studying early C++ implementation strategies, the source provides primary documentation that was previously unavailable. The Exhume methodology itself may also inform future reverse-engineering efforts targeting other legacy toolchains where original source has been lost.