> CRTs are analog. It's as many bits as your output hardware can make up
Actually the horizontal resolution of a CRT is limited by: the dot pitch of the colour phosphors, the bandwidth of the amplifiers, and the electron beam spread.
The vertical resolution is limited by a combination of: electron beam scan rate, delay for horizontal flyback/retrace, delay for vertical flyback, desired refresh rate, and electron beam spread.
There are more details for the resolution limitations, but I think I covered the main ones.
Actually the horizontal resolution of a CRT is limited by: the dot pitch of the colour phosphors, the bandwidth of the amplifiers, and the electron beam spread.
The vertical resolution is limited by a combination of: electron beam scan rate, delay for horizontal flyback/retrace, delay for vertical flyback, desired refresh rate, and electron beam spread.
There are more details for the resolution limitations, but I think I covered the main ones.