First, we've got to define what we mean by 'PC'. Are we talking IBM PC, or are we including 'home computers' like the Apple, Commodore PET, Atari 800, etc.? Are we including 'kit' computers, like the Altair 8800, Ohio Scientific Model 600, or the Heathkit H8?
Any of them could be a 'PC' in the sense of a 'personal computer' since they were all designed to be something that could be afforded by the hobbyist (ok, granted, the early efforts would have required a well-heeled hobbyist, but in an era when only governments and universities and large corporations had REAL computers, they were FAR cheaper).