Attributing credit for the Square hardware is tough. The WSJ article says Dorsey "engineered" the card reader. The blog post says no, it was Dorsey's friend,

Attributing credit for the Square hardware is tough. The WSJ article says Dorsey "engineered" the card reader. The blog post says no, it was Dorsey's friend, Jim McKelvey, who engineered the card reader. However, the blog post does not say that McKelvey, in turn, seems to have outsourced the engineering to Robert Morley, a hardware designer and EE professor in St. Louis (http://venturebeat.com/2009/12/15/professor-claims-square-took-his-credit-card-reading-technology/ http://venturebeat.com/2009/12/15/professor-claims-square-to...). This last connection seems plausible to me. I went to school with McKelvey and knew him slightly. Morley was a very well-known EE professor at our university, and a hardware hacker who founded a successful company called Micro-Term that made terminals, and later worked on hearing aid hardware which I'm not sure ever came to market. Exactly the kind of person a former CS major and glassblower like McKelvey might ask to do the design. The most recent summary I could find of the "who engineered the Square hardware" question is: http://techcrunch.com/2010/12/02/jack-dorseys-square-embroiled-in-nasty-litigation-over-card-reader-patent/ http://techcrunch.com/2010/12/02/jack-dorseys-square-embroil...