How many old videogame consoles ran at 60 FPS?
Zero.
That's sort of a technical answer, though. The NTSC television standard refresh rate is 59.94Hz for interesting reasons (that are maybe another post some other time) so we're already 0.1% off of 60Hz. That's not even the real issue, though!
Most consoles timed video output using oscillators and dividers, none of which had anything to do with NTSC television standards except through approximation. They displayed without dropped or skipped frames because unlike LCD screens, CRTs work off of whatever signal they get (though accepted tolerances differ). Furthermore, the spec is set for interlaced content and most consoles output non-interlaced video using a timing trick to get it to be non-interlaced at half resolution, so any console that can switch has at least two different refresh rates, neither of which will match!
Thus, consoles ranged from 1.08% below spec (the first PlayStation, which used dividers on the CD audio sampling rate!) to 0.26% above spec (the venerable NES, with the SNES just a hair behind). The closest were the Sega consoles and a few others, only 0.03% below spec.
Now, the C64 actually used the NTSC color carrier frequency... but with dividers that make the end result not quite match. Well, the newer ones were only 0.19% under; the older ones used different dividers that ended up a whopping 1.76% over!
Amusingly, in the PAL 50Hz regions the Sega consoles rank worst (0.6% under), the Nintendo consoles are nearly spot-on (0.01% under), and the old Playstation in interlaced mode is almost perfect with a deviation of only 0.0006% over!
And now the punchline: Due to weather, temperature, and other such, even an LCD monitor running at 60Hz will shift refresh rate slightly... so it's basically never perfect, but usually close enough.
...and now you know!
