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From: stevek@umcp-cs.UUCP
Newsgroups: net.micro,net.micro.pc
Subject: Re: 50 Hz computing
Message-ID: <2496@umcp-cs.UUCP>
Date: Thu, 8-Sep-83 19:11:21 EDT
Article-I.D.: umcp-cs.2496
Posted: Thu Sep  8 19:11:21 1983
Date-Received: Fri, 9-Sep-83 04:45:12 EDT
References: <1671@ihnss.UUCP> The problem with the power supply is non-existant in the apple
Organization: Univ. of Maryland, Computer Science Dept.
Lines: 25

and from another note I saw on this net  ditto for the IBM PC
but the display problem  is a more serious one.
	One solution is to use a DC video display (they run
$70 from a local surplus dealer for a new 10Mhz display) which will
use our (60Hz) synch. At least for the apple (II+)  it is "easy" to modify
(by jumpers on the motherboard) for 50Hz synch. Remember that 60Hz
USA standards use 15750Hz horizontal scan = 512 lines per frame, the
50Hz European standard works out to something like 600 lines per frame
(I do not remeber the exact number but 600 is a ballpark value) so that
if you try to use a 50Hz monitor if it works at all, more than "a little"
wiggle will occur - it will probably not work at all (I could be wrong).
	The bottom line is that if you buy a "system" micro like the
apple or IBM PC they planned it for world use. As far as the others
that supply a little transformer that plugs into the wall
1) find out if the manufacturer has a 220VAC 50Hz replacement 
2) unless the video can be jumpered; a 60Hz DC monitor used ;
 an external terminal (50Hz) is to be used ;
 or if one of the video display chips (like the 6845)
 is internal then a prom or patch program to reset it for the
50Hz scan.
	In any case good luck, I hope I have not gone into more detail
than is needed.
	Stephen Kogge
	Department of Computer Science
	University of aryland