Friday Archaeology: A Communist Apple II and Fourteen Years of Not Knowing What You’re Testing – Alexander Feldman's Blog

A personal essay blending computing history with formal methods research. The author traces the story of Bulgaria's Pravetz computers — Apple II clones built behind the Iron Curtain through reverse engineering — and connects it to the 1999 Hayes et al. paper that finally revealed what the ISCAS-85 benchmark circuits actually computed after 14 years of anonymous use in EDA research. The piece argues that reverse engineering, circuit synthesis, and fault diagnosis are mathematically equivalent problems (sharing the same ∃∀ quantifier structure), and contrasts this patient, understanding-driven approach with the current AI industry's 'build big and hope' methodology. The author also ties the history to their own PhD work and startup using model-based diagnosis tools on the very ISCAS-85 circuits Hayes decoded.