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From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: Insider Clock
Message-ID: <2779@cbmvax.UUCP>
Date: Sun, 15-Nov-87 05:58:47 EST
Article-I.D.: cbmvax.2779
Posted: Sun Nov 15 05:58:47 1987
Date-Received: Mon, 16-Nov-87 05:38:31 EST
References: <540@inria.UUCP> <729@neoucom.UUCP>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Organization: Commodore Technology, West Chester, PA
Lines: 35
Keywords: late french amiga

In article <729@neoucom.UUCP> wtm@neoucom.UUCP (Bill Mayhew) writes:
> In article <540@inria.UUCP>, rouaix@inria.UUCP (Francois Rouaix) writes:
> > 
> > I have somebody here on my BBS  who asks this question:
> > he has a Franch Amiga (french voltage 220v, 50 Hz)
> > He bought an Insider 1Mo expansion RAM with a permanent clock in the States.
> > The problem is that the clock is always late.
> 
> 
> You are correct in your assertion that your friend's Amiga
> gradually looses time becuase european power is 50 Hz, rather
> than 60 Hz.  The time-of-day on the Amiga appears to be incremented
> by an interrupt service routine that is triggered by a 60 Hz sqare
> wave from the power supply.  When the power supply is excited by 50
> Hz, fewer interrupts per second are generated, thus causing the
> clock to lag behind the proper time.

Sorry, this explanation doesn't cut it.  The Amiga software is supposed
to automatically sense whether the line frequency is 50 Hz or 60 Hz and
adapt accordingly.  It also senses separatly whether the system contains
a PAL or NTSC Agnus chip and sets up the appropriate window/screen size
parameters.

From the description, it sounds like the clock oscillator in the "Insider"
simply needs to be adjusted a little bit so it keeps correct time.  Look
for some sort of trimmer capacitor near the crystal that controls the
clock frequency.

I hope this answers the question, there are a fair number of ambiguities
here...

-- 
George Robbins - now working for,	uucp: {ihnp4|rutgers|allegra}!cbmvax!grr
but no way officially representing	arpa: out to lunch...
Commodore, Engineering Department	fone: 215-431-9255 (only by moonlite)