Origin of 'Straight 8' name

Back in the first half the 20th century, there were various configurations of 8-cylinder internal combustion engines. We're all familiar with the V-8, but there were inline 8-cylinder designs used primarily on luxury cars, making for a wonderfully long engine compartment. Cord, Buick, Packard, Chrysler and Oldsmobile all offered the "straight 8" on their high-end models. Those were called "straight-eights", I suspect because of the attractiveness of rhyming name. "Straight 8" configuration was also used on some aircraft as well. I suspect the name for the early PDP-8 is just a convenient adaptation of a once well-known automotive term, much like "V-8". For what it's worth, Ford experimented with an X-8 configuration as well, but never put it into production. --Chuck