Need to give credit to the Apple's cassette port interface, too, which not only ran as fast as the 1541 disk drive, but could be pressed into service as a rudim

Need to give credit to the Apple's cassette port interface, too, which not only ran as fast as the 1541 disk drive, but could be pressed into service as a rudimentary half-duplex 1200bps modem with the addition of a few inexpensive off-the-shelf parts to interface with the phone line. I've always been surprised that nobody else seems to have experimented with that. 1200 bps modems were nothing to be sneezed at in 1980.