The Percom one came with a 1771 already plugged into it.
I asked why - isn't that chip a little expensive to provide, if the
customer already has one that they had to unplug to plug in the board?
I am pretty sure the Radio Shack doubler came without the 1771 -- you
fitted the one that you had removed from the EI. Of course you were
supposed to have a Radio Shack service centre fit it, but I don't think
you had to (at least ont over here, I ordered a couple of upgrades for
other machines (like an extended color basic ROM for the CoCo) and fitted
them myself).
I think I;'d have been darn annoyed if I'd bought a doubler and ended up
with a redundant 1771. It was a rather expensive device...
One Percom rep told me that they tested and selected "the best" of the
1771s and supplied it, rather than have the customer using the random
quality one that they already had.
And what, pray tell, did Percom do with all those 1771s that didn't pass
these tests?
A different Percom rep told me that it was because they expected a large
percentage of their customers to "bugger up" the pins on their 1771 in the
process of unplugging it.
And people who couldn't remove a 40 pin socketed chip without mangling it
were surely not likely to make a good job of fitting the doubler board
with all the pins correctly aligned wit hthe socket.
-tony