ANALOG COMPUTER
Definition of Analog Computer: a computer that represents information by variable quantities (e.g., positions or voltages)
Analog Computer on wiseGEEK:
This means only analog computers can act as so-called “real computers” and solve some of the most complicated problems in mathematics. An analog computer can work both mechanically and electronically. Mechanical analog computers have existed for thousands of years, with the oldest known example being the Antikythera.
They transform and conduct operations on variables using mechanical, electrical, or other processes to directly alter the state of the media representing the variable. Mechanical analog computers have an ancient history. The Antikythera mechanism, a product of Ptolemaic Egypt, modeled the movements of objects visible in the sky, using a complicated series of gears.
What Is a Hybrid Computer?
Hybrid computers are computers that are designed to provide functions and features that are found with both analog computers and digital computers. The idea behind this combined or hybrid computer model is to create a working unit that offers the best of both types of computers. With most designs, the analog components of the equipment provide efficient processing of differential equations, while the digital aspects of the computer address the logical operations associated with the system.
By creating this type of integrated computer, the benefits of both analog and digital computing are readily available. A hybrid computer is extremely fast when it comes to managing equations, even when those calculations are extremely complicated. This advantage is made possible by the presence of the analog components inherent within the design of the equipment.
While the hybrid computer can manage equations with the same ease as an analog computer, the digital components help to eliminate one of the main drawbacks of a purely analog device. Comparatively speaking, the range of precision on an analog computer is limited, whereas the precision with a digital computer is much greater. By incorporating the components that allow the digital computer to go beyond the three to four digits of precision that are common with an analog equipment, hybrid computing makes it possible to handle equations much more rapidly than the digital option alone. In other words, hybrid computing offers both speed and precision, thus eliminating the need for the user to settle for one or the other.
The value of a hybrid computer is readily seen where there is a need to manage equations in a real-time fashion. Whereas a strictly analog device would provide quick returns that were not entirely precise, and a digital device would provide more precise responses that would take longer to calculate, the hybrid approach makes it possible to obtain answers now rather than later. At the same time, those answers are more detailed and thus more useful than the fast answers provided by the analog equipment.
It is important to note that a true hybrid computer is not simply a hybrid system. The hybrid computer is constructed with the components needed to allow the device to function with both speed and precision. Products that are marketed as hybrid systems are often nothing more than digital computer equipment that has been augmented with the presence of an analog to digital converter for the input, and a digital to analog converter to manage the output. While effective, a system of this type is normally considered less efficient than a true hybrid computer.
What Is a Digital Computer?
A digital computer is machine that stores data in a numerical format and performs operations on that data using mathematical manipulation. This type of computer typically includes some sort of device to store information, some method for input and output of data, and components that allow mathematical operations to be performed on stored data. Digital computers are almost always electronic but do not necessarily need to be so.
There are two main methods of modeling the world with a computing machine. Analog computers use some physical phenomenon, such as electrical voltage, to model a different phenomenon, and perform operations by directly modifying the stored data. A digital computer, however, stores all data as numbers and performs operations on that data arithmetically. Most computers use binary numbers to store data, as the ones and zeros that make up these numbers are easily represented with simple on-off electrical states.
Computers based on analog principles have advantages in some specialized areas, such as their ability to continuously model an equation. A digital computer, however, has the advantage of being easily programmable. This means that they can process many different sets of instructions without being physically reconfigured.
The earliest digital computers date back to the 19th century. An early example is the analytical engine theorized by Charles Babbage. This machine would have stored and processed data mechanically. That data, however, would not have been stored mechanically but rather as a series of digits represented by discrete physical states. This computer would have been programmable, a first in computing.
Digital computing came into widespread use during the 20th century. The pressures of war led to great advances in the field, and electronic computers emerged from the Second World War. This sort of digital computer generally used arrays of vacuum tubes to store information for active use in computation. Paper or punch cards were used for longer-term storage. Keyboard input and monitors emerged later in the century.
n the early 21st century, computers rely on integrated circuits rather than vacuum tubes. They still employ active memory, long-term storage, and central processing units. Input and output devices have multiplied greatly but still serve the same basic functions.
In 2011, computers are beginning to push the limits of conventional circuitry. Circuit pathways in a digital computer can now be printed so close together that effects like electron tunneling must be taken into consideration. Work on digital optical computers, which process and store data using light and lenses, may help in overcoming this limitation.
Nanotechnology may lead to a whole new variety of mechanical computing. Data might be stored and processed digitally at the level of single molecules or small groups of molecules. An astonishing number of molecular computing elements would fit into a comparatively tiny space. This could greatly increase the speed and power of digital computers.
