Analytical Engine

The Babbage Analytical Engine mostly used analog systems to implement some of the most basic functions of today’s digital computers. It used a series of punch cards for input, and relied on an analog printer for output. In terms of its capacity, the machine's use of an arithmetical unit and a primitive CPU that made use of physical pegs and rotating drums enabled the machine to become, in today’s terms, "Turing-complete," because it would have satisfied the criteria for a Turing machine, which was created in the 1900s.

Although the Babbage Analytical Engine was never physically completed, this early computer would have necessitated quite a lot of physical metal construction and a large footprint of dozens of cubic feet in terms of its overall size. Even so, it was an important precursor to early mainframe computers. More advanced mainframe units still had a lot of analog assemblies and extremely large physical footprints compared to today’s digital computers, which accomplish so much more by means of electrical impulse. One other interesting fact about the Analytical Engine is its resident memory, which is estimated to have been, according to design, about 16.5 kB.