Sorry, but by only considering early PCs you are ignoring most of the IT industry in that era. The PDP-11 came with full schematics, that was normal in the day,

Sorry, but by only considering early PCs you are ignoring most of the IT industry in that era. The PDP-11 came with full schematics, that was normal in the day, that was what "open" meant in the day to engineers. The early proprietary Unix systems, although they were proprietary and you couldn't share the code, they usually came with the source code. It was considered normal in that day to modify the kernel and recompile it. The PC business guys reused the term as part of their strategy, but for engineers it always meant something else.