In this episode, I take on the challenge of repairing my 1999 HP Omnibook 900B. After replacing the CPU in hopes of fixing the L2 cache errors, the diagnostics still report failures. But the story doesn't end there—this vintage laptop will still boot and run Windows 3.1 in Standard (286) mode, even though it refuses to run in Enhanced 386 mode. Join me as I explore the limits of this rare machine, dig into the diagnostics, and push it as far as it will go. This is the final episode in my HP Omnibook 900 restoration series, and even though the CPU swap didn't solve the problem, it's still fascinating to see what this machine can do. 🔧 What’s in this video: CPU replacement attempt on the HP Omnibook 900B Running diagnostics and hitting L2 cache failures Installing Windows 3.1 and testing Standard vs Enhanced modes Why this laptop is effectively a “Windows 3.1 only” system 👉 Don't forget to subscribe for more retro IT adventures: NT to Now #HPOmnibook #RetroComputing #Windows31 #VintageLaptop #RetroTech