Analytical machine of Babbage Charles: description, features, history and properties

Charles Babbage (1791-1871) - a pioneer in the development of computer technology, which developed two classes of computers - difference and analytical. The first of them received its name thanks to the mathematical principle on which it is based - to the method of finite differences. Its beauty lies in the exclusive use of arithmetic addition without the need to resort to multiplication and division, which is difficult to implement mechanically.

More than calculator

The Babbage difference machine is a counting device. She operates with numbers the only way she can, constantly adding them in accordance with the method of finite differences. It can not be used for general arithmetic calculations. Analytic Babbage machine is much more than just a calculator. It marks the transition from mechanized arithmetic to full-scale computation of general purpose. At different stages of the evolution of Babbage's ideas, there were at least 3 projects. Therefore, it is better to refer to its analytical machines in the plural.

Convenience and engineering efficiency

Babbage's computers are decimal devices in the sense that they use 10 digits from 0 to 9, and digital because they operate only with integers. Values are represented by gears, and each wheel is assigned its own wheel. If it stops at an intermediate position between integer values, the result is considered undefined, and the operation of the machine is blocked to show a violation of the integrity of the calculations. This is a kind of error detection.

Babbage also considered the use of numeration systems other than decimal, including binary and base 3, 4, 5, 12, 16 and 100. He settled on the decimal because of its habitual and engineering effectiveness, because it significantly reduces the number Moving parts.

Difference machine №1

In 1821, Babbage began working with a mechanism designed to calculate and tabulate polynomial functions. The author describes it as a device for automatically calculating a sequence of values with automatic printing of results in the form of a table. The integral part of the design is a printer that is mechanically connected to the calculation section. The difference machine No. 1 is the first complete construction for automatic calculation.

From time to time, Babbage changed the functionality of the device. The design of 1830 depicts a machine designed for 16 figures and 6 orders of difference. The model consisted of 25 thousand parts, divided equally between the computing section and the printer. If the device had been built, it would weigh 4 tons and would have a height of 2.4 meters. The work on creating the Babbage difference machine was stopped in 1832, after a dispute with the engineer Joseph Clement. State funding finally ceased in 1842.

Analytical machine

When work on the difference device stalled, in 1834 Babbage conceived a more ambitious device, which later became known as the analytical universal programmable computational mechanism. The structural properties of the Babbage machine correspond in many respects to the basic blocks of a modern digital computer. Programming is performed using punch cards. This idea was borrowed from a jacquard loom, where they serve to create complex textile patterns.

The logical structure of Babbage's analytical machine basically corresponds to the dominant design of electronic-era computers, which implies the presence of memory ("store") separated from the central processor ("mill"), sequential execution of operations and means for inputting and outputting data and instructions. Therefore, the author of the development received the title of pioneer of computer technology quite deservedly.

Memory and CPU

The Babbage machine has a "store" where numbers and intermediate results are stored, as well as a separate "mill", where arithmetic processing was performed. It had a set of 4 arithmetic functions and could perform direct multiplication and division. In addition, the device was able to perform operations, which now received the names of conditional branching, a cycle (iteration), microprogramming, parallel processing, fixation, pulse formation, etc. The author himself did not use this terminology.

The CPU of Charles Babbage's analytical machine , which he called the "mill," provides:

• Storage of numbers, operations on which are made immediately, in registers;
• Has hardware for the work with them of the basic arithmetic operations;
• Transfer of user-oriented external instructions to detailed internal management;
• A synchronization system (tact) for executing instructions in a carefully selected sequence.

The control mechanism of the analytical machine performs the operations automatically and consists of two parts: the lower level, controlled by massive drums called barrels, and a high level using punched cards developed by Jacquard for weaving looms widely used in the early 1800s.

Output Devices

The result of the calculations is displayed in various ways, including printing, punched cards, plotting and automatic production of stereotypes - trays made of soft material, on which an impression is produced, which can serve as a mold for casting plates for printing.

New design

Innovative work on the analytical machine Babbage basically completed by 1840 and began to develop a new device. In the period from 1847 to 1849 he finished the development of difference machine No. 2, which was an improved version of the original. This modification was designed for operations with 31-bit numbers and could bring into the tabular form any 7th-order polynomial. The design was elegantly simple and required only a third of the number of parts of the original model, providing the same computing power.

In the difference and analytical machines of Charles Babbage, the same design of the output device was used, which not only made a printout on paper, but also automatically created stereotypes and independently produced formatting according to the page layout set by the operator. In this case, it was possible to adjust the height of the row, the number of columns, the width of the fields, automatic collapsing of rows or columns, and the arrangement of blank lines for readability.

Heritage

In addition to several partially created mechanical assemblies and test models of small work sections, none of the designs were implemented fully during the life of Babbage. The main model collected in 1832 was 1/7 of the difference machine No. 1, which consisted of approximately 2,000 parts. It works flawlessly to this day and is the first successful automatic computing device that implements mathematical calculations in the mechanism. Babbage died when a small experimental part of the analytical machine was assembled. Many details of the design are preserved, as well as a complete archive of drawings and notes.

The projects of Babbage's huge mechanical computers are considered one of the most amazing intellectual achievements of the 19th century. Only in the last decades his work has been studied in detail, and the degree of importance of what he did is becoming more and more obvious.