Most modern computers are based on what is called the “von Neumann architecture,” which consists of an input device, a central processing unit (CPU), random access memory (RAM), and an output device.
This layout, however, is not at all fundamental to computation. Other computation devices were used before the invention on the von Neumann architecture, and many other possibilities for computing platforms have been proposed, ranging from arrays of subatomic particles to the structure of DNA....
Most modern computers are based on what is called the “von Neumann architecture,” which consists of an input device, a central processing unit (CPU), random access memory (RAM), and an output device.
This layout, however, is not at all fundamental to computation. Other computation devices were used before the invention on the von Neumann architecture, and many other possibilities for computing platforms have been proposed, ranging from arrays of subatomic particles to the structure of DNA. In spite of this seeming complexity, there are only three operations necessary to compute anything that is computable. To understand this, we can look at the “register machine”.
The concept of the register machine was introduced by Hao Wang in 1957 and has helped form the foundation of modern computing. The register machine is an idealized, imaginary (but completely possible) machine that consists of only a finite number of registers (modern computers contain millions or billions) and a single processing unit.
A register is a discrete memory location that contains a single integer (0, 1, 2, 3, to infinity). The processing unit carries out just three possible instructions, one at a time:
Increment register ( add 1 to the contents of the current register and go to the next step)
Decrement register (subtract 1 from current register and move to next step), or if the register contains 0, branch to next step
End (stop the program)
A program written for a register machine, using just these three instructions, can compute anything any computer can compute. Register machines are considered “unlimited” or “universal” machines because they can simulate any other computing machine. They can run any program any computer is capable of running.
There are no limitations on what a register machine must be constructed from. The calculations can be done by hand with a pencil and paper, on a silicon chips in your laptop, or on quantum particles. The only difference is the speed of the computations. Modern computers can execute millions or trillions of these computations every second.
The main point here is that there are a set of most basic principles of computation that all computers follow. All of the complexity we see in computers are just more advanced ways of carrying out these functions in faster, more streamlined ways.
To read more about how register machines work and the implications of their simplicity and power, please see the link below:
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