Re: ZIPGS 2-pin Crystal

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

andrew.webber2@btinternet.com (Andrew Webber) wrote in message news:<6b297ed0.0206100144.620d389d@posting.google.com>...
> 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 :-)
> 
> AndrewA

I just snipped the crystal and put in a 32Mhz oscillator. All worked
ok :-).
 
I then put in a 40Mhz oscillator and the system did not start, just a
single character appear on screen. I still have to change the SRAMs so
I think thats the cause.

Does that sound right?

Cheers

Andrew