Re: mini-FAQ: upgrading TransWarp GS/Zip GS

[blasjw@ntmtv.com (Joseph Blas)]

In article <CA8u40.5Ho@wave.scar.utoronto.ca> 90taobri@wave.scar.utoronto.ca (Brian Tao) writes:
>In article <mdmCA7xD9.Aqq@netcom.com>, Mark Miller writes...
>> 
>> When you install your new 4-pin crystal, be aware that it must be placed
>> near the bottom end of the socket.  
>
>    Bottom end?  This is what the underside of the crystal and the
>socket look like:
>	 _____	
>	|-----|		 ____
>	|o   o|		|.  .\
>	|o   o|		|    |
>	|o   o|		|    |
>	|o   o|		|    |
>	|o   o|		|    |
>	|o   o|		|    |
>	|o   o|		|.  .|   
>	|-----|		\____/
>
>	socket		crystal
>
>    The crystal is the same length of the socket, but only pins 1, 7, 8
>and 14 are present.  Three corners are rounded and one is "sharp".  I'm
>told the sharp corner should go in the upper-left corner.  Can someone
>confirm this?  If that's right, Frank should add this to the FAQ.
>--
>Brian Tao:: taob@io.org (Internex Online, 416-363-3783, 10 lines, v.32bis)
>::::::::::: 90taobri@wave.scar.utoronto.ca (University of Toronto, 9T4)
>

     Yes, there are only four pins and one of them is not used. The
other three are GND, +5v, and the clock output.  Looking at the
crystal from the top, the pin assignments would look like this:

                      ____
                 +5v |.  .\ CLK
                     |    |
                     |    |
                     |    |
                     \.__./ GND


     The reason that one of the corners is sharp is to denote the
location of pin 1 on the Crystal.  Other common markers to denote pin
one are a dot or dimple.  As far as on the circuit board itself, a dot
or a litte 1 often mark the spot.  Now, with a socket, usually you can
tell were pin one is by looking for a little semicircle at one end.
The semicircle denotes the top of the socket so pin one would be the
top left pin.  BTW, many DIPs have this semicircle also.  Here is a
little diagram to show what I mean:

                        ___   ___
                 pin 1 |.  \_/  |
                       |        |
                       |        |
                       |        | 
                       |        |
                       |        |
                       |        |
                       ----------

     
      I realized there is some other info pertinent to add.  Generally
for any DIP, the number scheme is as follows:  Looking at the top,
pin 1 is in the upper left corner.  The numbers increment down the left
side.  Then, they increment up the right side.  Here is another
diagram:

                       ______
                    1 |.   .| 14
                    2 |.   .| 13
                    3 |.   .| 12
                    4 |.   .| 11
                    5 |.   .| 10
                    6 |.   .| 9
                    7 |.   .| 8
                      -------

       Also, in most cases (MPUs excluded), the power will be the
upper left pin (pin 1) and the ground will be the lower right pin. 

       Now, with the backgound out of the way... On to your question.
Yes, assuming that the top of the socket is up, the sharp corner of
the crystal would go in the upper left.  This is probably the case
but, you should look for the clues I mentioned to be sure.  It could
be oriented the other way which would mean pin 1 is in the lower
right. 

       If anyone has any corrections or additions, feel free to post
them.  

                Hope this helps,

                        Joe


          
                      
-- 
Joseph W. Blas   | "suburbs have no charms |Apple-----  -----   -----  -----
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Mt. View, CA     |  - Neil Peart           |   -----  -----   -----  -----Rules!