Wizard wrote:
Those one round and slot holes is for manufacturing
process, simply
drops onto bed with two precision-machined pins to keep things in
alignment. This is especially necessary because chip bonding and
wire bonding, lid placing and soldering process is mostly mechanical.
Later on when processing becomes powerful enough for optical
alignment on the fly, that holes disappeared.
Thanks, Wizard, and also to the others that replied.
When I saw it all that could come to mind was that maybe they were
related to holding the chip in the board it was destined for ... I
remember an ECG machine I wrote the software for where the 68000 (the
*large* DIP) in the prototypes had to be "tied down" with a cable tie
around the socket to stop itself from thermally walking out of it! I
read that the Apple III had a similar problem with a lot of it's chips.
Ben
P.S. Just for the record I'm not a chip collector, although I can't
blame a scrapper for selling off whatever he can of a system that's
destined to be recycled. Obviously it's too bad if a collectible machine
gets scrapped, but the number of collectors isn't large enough to ensure
otherwise.