In a message dated 95-12-28 13:09:57 EST, maney@MCS.COM (Martin J. Maney)
wrote:
>Oops, I cut one bit I wanted to inquire about.  You, like others I've
>seen, specify connecting only one each ground and power line to the ZIF
>socket.  The 28 and 40 pin PICs (at least the 73 and 74) have two gounds
>and two each ground and +5 respectively, and I'm wondering if anyone has
>asked Microchip about reccomended wiring for these redundant(?) pins
>during programming of the chips.  I wired the ZIF up to connect both the
>pins for the 16C73s I knew I'd be working with, and it doesn't seem to
>have done any harm, but every time I see someone describe wiring only one
>of each pin for a ZIF socket I wonder about this...
>
>

   A few weeks ago I was using a '74 with +5 and ground wired to only one of
the two pairs of power pins.  I forget now whether it was erratic operation,
or no operation, but in any event the chip made it very clear that it wanted
_both_ pairs connected.  It was easy to do an A-B test, and I did several of
them with consistent results.
   However, I didn't look into other possible explanations for the problem -
perhaps I had a marginal noise situation where the noise was cured by osmosis
when making the second connection (although I use both disc and electrolytic
bypasses), or perhaps I had an atypical chip - dunno.  Or maybe something
else strange.
   In any event, from now on I'm going to use both pairs for sure!
   Would appreciate definitive answer if anybody gets it from Microchip!!

...Shel Michaels