Panasonic and Sony spent years jockeying for a lead in the broadcast video market. In 1982 Sony launched Betacam, a pro version of consumer Betamax and within 3 years had sold 30,000 to broadcasters round the world. Betacam was special because it recorded the black-and-white luma signal, and two colour difference signals, as separate ‘components’ in adjacent helical tracks laid down by separate heads on the rotating drum.
Panasonic refused to back Beta, and developed the rival M format based on the domestic VHS cassette. RCA sold it as Hawkeye and Ampex made a version called Recam. M format worked like Betacam by recording the luma on one track of the tape and the two chroma signals together on an adjacent track. But whereas Sony compressed the chroma signals in time, and recorded one after the other, Panasonic recorded them simultaneously, at different frequencies. Picture quality was poor.
In 1985 Japan’s state broadcaster NHK helped Panasonic modify M to MII. The cassette was slightly changed so that is was not quite the same as VHS, and loaded with high quality metal powder tape that needed new recording heads. Sony responded by upgrading Betacam to SP, keeping the broadcasters happy by retaining some compatibility with all existing Betacam recorders.
Whilst a few TV stations including Anglia and Thames bought MII recorders, they complained about the poor sound, and awkward system of entwining the FM audio with the video. So Panasonic made more changes to record audio as digital PCM code. But there was then not enough room on the tape for an analogue soundtrack to use as an editing guide. MII never officially died. Panasonic just stopped promoting it.
In the 1990s Panasonic had far more success with with DVC-Pro, a professional version of the consumer Digital Video Camcorder.