expansion differences (was Re: Micro$oft Biz'droid Lusers)

The Apple][ didn't really need a lot of plugging. It was designed to be a computer, though its predecessor, the Apple I had signal names on its schematic that clearly indicated it was intended as a video device more than as a general purpose computer. That was probably reasonable since everything had to be slaved to the video refresh timing. The TRS-80 was in the stores nearly a year before the expansion interface, disk drives, and OS were available. I don't know what the story on the PET was, as there were no outlets for them here in the Denver area that kept 'em in stock. They certainly didn't have an OS or anything of the sort until well after their market window in the U.S. had closed. AFAIK, their successes were mainly in the European market. I remember seeing their ads in mags brought back from Europe, but in the entire time I was looking ad commercial systems, the only PET I ever saw, in private hands or in the hands of a merchant, was the original 4K PET with the toy (Chiclet?) keyboard. The C64 doesn't fit in the same generation with these early machines.

The serial printers of the time seemed to work fine at low baud rates since they were most often the daisywheel types. Those cost WAY more than a person wishing to save money on a $399 CoCo would have wanted to pay.

It IS the most important part of the computer, since it's what you saw. The user interface seems, still, to be the primary issue in deciding on one system over another for home use. It's like the speakers in your sound system. I normally tell people to spend at least half their home stereo budget on speakers, half the remainder on their receiver/amplifier, and the remainder on signal sources.

True, not to mention that, back then, (1980) they were the only computer maker with a world-wide retail/service/distribution network.

That's something I wasn't aware of, though I still maintain that RS really didn't intend for it to be used for 3rd party hardware. They certainly didn't provide paths, in general, by means of which one could expand a system beyond their own designs, which other mfg.'s often (possibly unintentionally) did.