*BSD News Article 6720


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From: roell@informatik.tu-muenchen.de (Thomas Roell)
Subject: Re: Question on Diamond Clock Synthesizer
In-Reply-To: curtis@cs.berkeley.edu's message of 11 Oct 1992 00:49:20 GMT
References: <1b7tmgINNi06@agate.berkeley.edu>
Sender: news@Informatik.TU-Muenchen.DE (USENET Newssystem)
Organization: Inst. fuer Informatik, Technische Univ. Muenchen, Germany
Date: Mon, 19 Oct 1992 08:24:20 GMT
Message-ID: <1992Oct19.082420.16353@Informatik.TU-Muenchen.DE>
Lines: 30

>(1) Can Diamond's "programmable" clock synthesizers generate
>_any_ frequency?  Could they thus be used to drive a fixed-scan
>monitor?

Yes, you can programm almost ANY frequency with that chip. There are a
few limitations like the highest frequency the chip can produce
(without emitting that neat smoke) and the resolution of the
programming algorithm itself.

>(2) Has anyone considered trying to reverse-engineer Diamond drivers
>to discover the interface to the clock synthesizer?  It doesn't
>seem like it'd be that hard.

That won't help you that much. In the BIOS you'll find a list of
values you can programm the PLL to which was considered useful by the
BIOS writer (i.e. all frequencies you use for the BIOS modes). But it
won't give you the information HOW to programm other frequencies. The
next thing (and I belive that was Diamonds major reason not to pass
the things away) is that there are more revisions of boards with more
different PLLs than you moght believe. Should I really tell you that
they all use the same basic chips, but have to be programmed a little
bit different to get the desired results ? So what would happen if you
programm the PLL wrong and blow your board ? Who is liable for this ? 

- Thomas
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