Charles Babbage (1791–1871) - a pioneer in the creation of computer technology, who developed 2 classes of computers - difference and analytical. The first of them got its name thanks to the mathematical principle on which it is based - the finite difference method. Its beauty lies in the exclusive use of arithmetic addition without the need to resort to multiplication and division, which are difficult to implement mechanically.
More than a calculator
The Babbage difference machine is a counting device. She operates with numbers in the only way she is capable of, constantly adding them in accordance with the finite difference method. It cannot be used for general arithmetic calculations. Babbage’s analytical machine is much more than just a calculator. It marks the transition from mechanized arithmetic to full-scale general-purpose computing. At various stages in the evolution of Babbage's ideas, there were at least 3 projects. Therefore, his analytical machines are best referenced in the plural.
Convenience and engineering efficiency
Babbage computers are decimal devices in the sense that they use 10 digits from 0 to 9, and digital because they operate only with integers. The values ​​are represented by gears, and each wheel has its own wheel. If it stops in an intermediate position between integer values, then the result is considered undefined, and the machine is blocked to show a violation of the integrity of the calculations. This is a peculiar form of error detection.
Babbage also considered the use of number systems other than decimal, including binary and with a base of 3, 4, 5, 12, 16, and 100. He settled on decimal because of its familiarity and engineering efficiency, since it significantly reduces the number moving parts.
Difference machine No. 1
In 1821, Babbage began developing 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 the results in a table. An integral part of the design is a printer mechanically connected to the design section. Difference machine No. 1 is the first full-fledged design for automatic calculations.
From time to time, Babbage changed the functionality of the device. The 1830 design depicts a machine designed for 16 digits and 6 orders of magnitude difference. The model consisted of 25 thousand parts, divided evenly between the computing section and the printer. If the device had been built, it would have been estimated to be 4 tons and had a height of 2.4 m. The work on creating the Babbage difference machine was stopped in 1832, after a dispute with engineer Joseph Clement. State funding finally ceased in 1842.
Analytical machine
When work on the difference apparatus stalled, in 1834 Babbage conceived a more ambitious device, which later became known as the analytical universal programmable computing mechanism. The structural properties of the Babbage machine are largely consistent with the main blocks of a modern digital computer. Programming is done using punch cards. This idea was borrowed from the jacquard loom, where they serve to create complex textile patterns.
The logical structure of the Babbage analytical machine basically corresponds to the dominant design of computers of the electronic era, which implies the presence of a 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
Babbage’s machine has a “store” where numbers and intermediate results are stored , as well as a separate “mill” where arithmetic processing was performed. She had a set of 4 arithmetic functions and could perform direct multiplication and division. In addition, the device was able to perform operations, which are now called conditional branching, loop (iteration), microprogramming, parallel processing, fixing, pulse generation, etc. The author himself did not use such terminology.
The CPU of Charles Babbage’s analytical machine , which he called the “mill,” provides:
- storing numbers, operations on which are performed immediately, in registers;
- has hardware for performing basic arithmetic operations with them;
- transfer of user-oriented external instructions to detailed internal control;
- synchronization system (beat) for executing instructions in a carefully selected sequence.
The control mechanism of the analytical machine performs operations automatically and consists of two parts: the lower level, controlled by massive drums called barrels, and the high level, using punched cards developed by Jacquard for looms, which were widely used in the early 1800s.
Output devices
The result of the calculations is displayed in various ways, including printing, punch cards, graphing, and the automatic production of stereotypes - trays of soft material on which the result is printed that can serve as a mold for casting plates for printing.
New design
Babbage basically completed the pioneering work on the analytical machine by 1840 and began to develop a new device. In the period from 1847 to 1849, he completed the development of differential machine No. 2, which was an improved version of the original. This modification was designed for operations with 31-bit numbers and could lead to the tabular form of any 7th order polynomial. The design was elegantly simple and required only a third of the number of parts of the original model, providing equal processing power to it.
Charles Babbage difference and analytical machines used the same design of the output device, which not only printed on paper, but also automatically created stereotypes and independently formatted according to the page layout set by the operator. At the same time, it was possible to adjust the row height, number of columns, field widths, automatic folding of rows or columns, and arrangement of empty rows for easy reading.
Heritage
In addition to several partially created mechanical assemblies and test models of small working sections, not one of the structures was fully implemented during Babbage's life. The main model assembled in 1832 was 1/7 of the difference machine No. 1, which consisted of approximately 2 thousand parts. It works flawlessly to this day and is the first successful automatic computing device that implements mathematical calculations in a mechanism. Babbage died when a small experimental part of the analytical machine was assembled. Many design details are preserved, as well as a complete archive of drawings and notes.
Babbage's enormous mechanical computing projects are considered one of the stunning intellectual achievements of the 19th century. Only in recent decades has his work been studied in detail, and the importance of what he has done becomes more and more obvious.