The future 'memex' desk described by Bush reminded me of what early computers were like. It's interesting that he doesn't specifically mention any of these computers by name, although they were around for a few years before this article was published. The first programmable computer was shown in May of 1941. Maybe it wasn't as widely understood that the computer could be much more than a huge calculator, so devices like the Vocoder (p.8) that people could see and hear right away were more interesting at the time.
Konrad Zuse's Z3- World's First Programmable Computer