While the LGP-30(vacuum tube/drum), G-15(vacuum tube/drum), and PB-250(transistor/delay lines) predated it, the ground-breaking Olivetti Programma 101(transistor/delay line) programmable desktop calculator was officially called a "personal computer" in some of its advertising and sales literature. It was introduced in October of 1965.
Late in the game as far as single-user, standard AC-line-powered computing devices compared to those machines and probably others, but those machines, AFAIK, were not advertised nor specified as "personal computers". That said, I am much more aware of electronic calculator history than computer history, so I could be entirely biased here. Also, the Programma 101, as I've stated here before, only scratches the definition of a true computer in that it is not capable of handling any data type but floating point binary-coded decimal numbers, has very limited data storage capability, and had no peripheral interfacing capability. There were quite a number of single-user computing devices made and sold that ran on standard AC power, and were vastly more capable than the Programma 101, and predated it, but, AFAIK, were not advertised or particularly marketed as "personal computers". One that comes to mind is the Monroe Monrobot III(vacuum tube/drum), introduced in February, 1955. Another is the IBM 610 "Auto Point"(vacuum tube/drum) computer, introduced in 1957. It was originally named the "Personal Automatic Computer" (PAC) by its designer. I'm sure that there are quite a few other machines developed in the mid-to-late 1950's that would qualify as personal computing devices, but these two are the ones that I'm aware of that seem to fit the bill. Some of these may actually have been capable of manipulating data types other than decimal numbers. In 1962, Casio introduced its AL-1 programmable (up to 360 steps) relay-based electric calculator. It was definitely intended as a personal computing device, and calculations could be performed manually from a keyboard much like a regular calculator, but also automatically via plastic toothed gears that would have teeth broken off of them to encode program steps. The gears would be electrically read by the machine and directed the machine to perform computer-like operations. I'm not arguing that any of these, including the Programma 101, are the first "personal computers" by any means. I'm just adding some thoughts to the discussion. Rick Bensene The Old Calculator Museum https://oldcalculatormuseum.com
