Re: Q: Swapping Motherboards on GS --> Damage hazard?

["Roger Johnstone" <rojaws@es.co.nz>]

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In article <39AD8C3B.4E06C51A@aol.com>, Marsha Jackson <menacechgo@aol.com>
wrote:


>(To sender&group)
>
>The 7(actually 6) pin power connector and volktages are the same so that part
>presents no problem, the problem is the US based motherboards I put out NTSC
>composite video instead of PAL.

My IIgs (a Woz edition, bought in New Zealand where we use PAL) has NTSC
composite video. I would be interested to know if anyone out there has seen
a PAL IIgs. The extended keyboard IIe from the same era was also NTSC only.
In New Zealand the Apple dealers sold Apple NTSC colour monitors to go with
them, for a high price of course. I've always suspected the real reason
Apple changed to NTSC-only was so they could sell their very expensive
monitors.

>I don't have my hardware reference handy, so I'm not sure if this would really
>affect the 15pin RGB output or not.

It won't. The composite video is generated using an MC1377 encoder chip
driven by the RGB signals. I believe the chip used can be switched to
generate either PAL or NTSC. A simple hardware hack could change it to PAL
but the encoder also needs a colour reference signal. For NTSC it uses
3.58MHz which is also used for other things on the board e.g. the ADB
microcontroller's clock. You would have to add a 4.43MHz clock for PAL.
Altogether too much work, why did I even mention it?  :-)


Roger Johnstone, Invercargill, New Zealand
http://homepages.ihug.co.nz/~rojaws
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As a computer, I find your faith in technology amusing.