John Graham-Cumming, a computer programmer and author, has launched Plan 28, a project to build a working Analytical  Engine, which was first proposed by Charles Babbage in 1837. Babbage’s Analytical Engine (AE) design — to be constructed of brass and iron — included a mill (which is in essence a central processing unit), and the store, which is an expandable memory unit. The AE was to be run with programs stored on punch cards, which could be also be used as data input devices. Within the mill, Babbage proposed to manipulate operations with barrels, which were to be cylinders with protruding studs. Data transfer was to occur from the store to the mill where the data would be processed and then transferred back to the store. Babbage also planned for a printer and plotter as output devices. Punch cards would  have been used as external data storage. The AE would have been powered by steam and the machine would be approximately the size of a steam locomotive.