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From: grr@cbmvax.UUCP (George Robbins)
Newsgroups: comp.sys.amiga
Subject: Re: Problem with JTIME
Message-ID: <2305@cbmvax.UUCP>
Date: Fri, 4-Sep-87 22:08:06 EDT
Article-I.D.: cbmvax.2305
Posted: Fri Sep  4 22:08:06 1987
Date-Received: Sun, 6-Sep-87 02:01:30 EDT
References: <30@rpicsb8>
Reply-To: grr@cbmvax.UUCP (George Robbins)
Distribution: na
Organization: Commodore Technology, West Chester, PA
Lines: 31
Keywords: JTIME, clock/calendars, hardware

In article <30@rpicsb8> guilford@csv.rpi.edu (Jim Guilford) writes:
> []
> 
> I recently built "JTIME: a Real-Time Clock for the Amiga" by Micharl Keryan.
> It is a clock/calendar that plugs into the second joystick port. The plans
> and description came on an amiga disk (I forget where I got the original
> from. It might have been a fish disk or a BBS, but I can't recall). It is
> based around the RTC58321 clock/calendar chip by SaRonix. I ordered the chip
> from Jameco, who give the part number as MSM58321RS.
> 
> After wiring up a small circuit board, I inspected it and tested it. It
> didn't work. I pulled the chips, did some more testing, and found a short
> between two wires, I fixed that, repopulated the board, and plugged it in. I
> found that I could read and write the date/time with no problem, but that
> the time was not advancing. It seemed to be doing a good job of emulating a
> battery backed up slice of ram!

I suspect that the RTC58321 is a hybrid package containing an OKI MSM5831
clock chip and a watch crystal, if not a battery.  Since the OKI chip you
got from Jameco needs an external watch crystal, the board just sits there
looking stupid. 

Solution:  check out the JTIME info more carefully and either add a watch
crystal or get hold of the saronix part.  Sometime the people who cook up
these projects get carried away and forget to use least common denominator
parts that are easy to find.

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