[time-nuts] 60Hz mains clocking in computers

Poul-Henning Kamp phk at phk.freebsd.dk
Sun Dec 13 16:53:53 UTC 2009


In message <4B251964.5040808 at rubidium.dyndns.org>, Magnus Danielson writes:
>Joe Gwinn wrote:

>> The exception to this was that video generators were (and still 
>> are) often locked to the AC line so that hum bars would not drift across 
>> the screen.
>
>I have never seen this in any of the devices I've seen. It is certainly 
>not what we do in the TV world either. Examples would be good.

This feature disappeared with color television, specifically NTSC, which
tweaked the vertical frequency just a tad lower than 60Hz.

Poul-Henning

PS: But NTSC gave us the 14.31818181.. MHz frequency, as imortalized
by the ghastly colors of the IBM CGA.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.



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