Exploring Abstractions of a General-Purpose Computer by Developing a Mini Breadboard Computer

The idea of using multiple layers of implementations and abstractions is adopted behind all complex elements around. By this concept, the complicated thing is broken down into simpler layers, each layer is implemented and a mask of abstraction is made over it. Thus for someone to build something above a layer, he need only know the interface, allowing one to be comfortable and concentrate on specific layers. The operating systems that are used in PCs are such abstractions. The interface is so good that its like magic. But this conceal is disturbing for some curious people. Having an idea of deeper implementations can also give a better understanding and hence help achieve a better realization of the respective layer. Grasping the concept of abstractions and implementations enables one to work on something complex using it, decimating the complicated ideas into simpler layers. This paper tries to follow an analogous approach to the whole implementation top to bottom of a general-purpose computer in a layman's perspective. The analogy used is a miniature computer, containing a simple OS, made on a breadboard using an 8-bit microcontroller, an LCD screen and an Android app used as the keyboard.