Re: ZIPGS 2-pin Crystal

[andrew.webber2@btinternet.com (Andrew Webber)]

blackm00@cam.org (Michael Black) wrote in message news:<6447bcd3.0206081022.28844b4c@posting.google.com>...
> andrew.webber2@btinternet.com (Andrew Webber) wrote in message news:<6b297ed0.0206080046.3e7ea406@posting.google.com>...
> > andrew.webber2@btinternet.com (Andrew Webber) wrote in message news:<6b297ed0.0205292353.68093fc8@posting.google.com>...
> > > Hi,
> > >
> > > Quick question. I am trying to upgrade (Yes I have posted before ;-))
> > > my ZIPGS and have read all the FAQs. The ZIPGS 8/16 I have is a 1.01
> > > revision and has a soldered 2-pin crystal. There is a socket on the
> > > card to accept a 4-pin TTL Oscillator, but this is currently empty. I
> > > have also read the Hypercard stack.
> > >
> > > Now my question, can I just snip (suggested in the Stack) the 2-pin
> > > crystal off the board and then plug in a standard 4-pin oscillator?
> > >
> > >
> > > Thanks
> > >
> > > Andrew
> >
> > I recieved my 65c816-14 from WDC and replaced the old 65c816-7. All
> > works find, but I still want to push the board above 8Mhz. Please :-)
> > can anyone tell me if my ZIPGS will stop functioning if I snip the 2
> > pin crystal (labeled x2) off the board and utilise the empty
> > Oscillator (Labeld x1) socket with a 4-pin oscillator?
> >
> > The FAQ says there is extra curcuitry for for the 2-pin crystal
> > (canister), so if I just snip it and put a 4-pin in is the board
> > intellegent enough to know which one to use?
> >
> > Sorry if you are getting bored with my post....just to don't want to
> > screw my working ZIPGS!
> >
> > Andrew
> 
> I don't know about that specific equipment.  But it wouldn't be
> a matter of intelligence.
> 
> There'd be a gate somewhere, and both the input and output are brought
> out so the crystal can be connected to their.  With the crystal there,
> the gate acts as an oscillator.
> 
> But if the crystal isn't there, it's just a gate.  So a signal fed
> to the pin that connects to the input pin of the gate would simply
> be buffered by the gate, and then get into the rest of the circuit,
> where it couldn't tell whether the gate was buffering or oscillating.
> 
> A lot of ICs are designed that way, so whether or not a piece of
> equipment has the layout for an external oscillator, it often will
> work.
> 
> If you have electronic background, it would be easy to take an ohmeter
> of some kind, and see if one of the pins of the crystal connect to
> the pin that is the output of the plug-in oscillator.  If that's the
> case, one could be pretty certain that just clipping one  of the leads
> of the crystal, and plugging in the oscillator would work.
> 
>    Michael


Thanks Michael... I think its going to be a snip it and see :-)

Andrew