Soon after the introduction of the Apple IIe, the Apple engineers realised that the video bandwidth doubling circuitry used to implement 80-column text mode could be easily extended to include the machine's graphics modes.
12.
The legacy ITU Rec . 601 4 : 3 image size is used for its compatibility with the original video bandwidth that was available for professional video devices that used fixed clock rates of a SMPTE 259M serial digital interface.
13.
Here " t " sweep is the sweep time, " k " is a dimensionless proportionality constant, " f " 2 & minus; " f " 1 is the frequency range of the sweep, RBW is the resolution bandwidth, and VBW is the video bandwidth.
14.
These formats extend the width of the " Full " configuration by utilizing 8 unused bits and reassigning the 8 redundant framing / enable bits to produce a data path width of up to 80 bits over two connectors / cables, which further increases the video bandwidth.
