Lack of 8-bit threads (was Re: Linux question)

Tony Duell ard at p850ug1.demon.co.uk
Sun Apr 22 15:30:19 CDT 2007


> 
> Chuck Guzis wrote:
> > I recall in 1983 how difficult it was to even *order* a 220V 50Hz 
> > 5150 from IBM.  The IBM sales office people just shrugged their 
> 
> If the entire system was designed around the NTSC frequency (and one 
> would assume the 60Hz AC power to match) then how did a "euro" IBM PC 
> work?  Did it have 60Hz CGA as well?

Nothing in the PC depends on the mains line frequency. All the outputs 
from the PSU are DC, there's not even a mains-frequency heartbeat signal. 
All the timing comes from crystal oscillators (one on the motherboard, 
maybe on the expansion cards too).

A European PC with a CGA card will output 60Hz NTSC video. Europ[ean TVs 
in general won't display that (wel, modern ones probably do, but 25 years 
ago they didn't), but the 5153 monitor (IBM CGA monitor) doesn't depend 
on mains frequency either, and will work find on 50Hz mains of the 
appropriate voltage

-tony



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