High Definition

The BBC introduced high-definition television in 1936, with 405 total scanning lines (well, it was HDTV by the standards of the time). Modern HD started in the 1980s with a Japanese analog standard, 1125/59.94, with 1035 active scanlines, interlaced. Europe also developed an interlaced analog system, called Eureka, using 1250 scanlines total and running at 50 fields per second. Both systems used the 16x9 widescreen aspect ratio.

Both systems have been made obsolete by digital HD standards, and any program content you encounter from the earlier systems will have to be (and probably already has been) converted to one of the current standards, since analog HD capture cards for the Mac are nonexistent.