Charles Babbage (1791-1871) - a pioneer in the creation of computing technology, who developed 2 classes of computers - difference and analytical. The first of them got its name due to the mathematical principle on which it is based - the method of finite differences. Its beauty lies in its exclusive use of arithmetic addition without having to resort to multiplication and division, which are difficult to implement mechanically.
More than a calculator
Babbage's Difference Engine is a counting device. She manipulates numbers in the only way she can, constantly adding them up according to the method of finite differences. It cannot be used for general arithmetic calculations. Babbage's Analytical Engine is much more than just a calculator. It marks the transition from mechanized arithmetic to full scale general purpose computing. At different stages of the evolution of Babbage's ideasthere were at least 3 projects. Therefore, his analytical engines are best referred to in the plural.
Convenience and engineering efficiency
Babbage's computers are decimal in the sense that they use 10 digits from 0 to 9, and digital in that they operate only with whole numbers. Values are represented by gears, and each digit has its own wheel. If it stops at an intermediate position between integer values, then the result is considered indeterminate, and the machine is blocked to show a violation of the integrity of the calculations. This is a form of error detection.
Babbage also considered the use of number systems other than decimal, including binary and base 3, 4, 5, 12, 16, and 100. He settled on decimal because of its familiarity and engineering efficiency, since it greatly reduces the number of moving parts.
Difference Engine 1
In 1821, Babbage began development 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 the form of a table. An integral part of the design is a printer mechanically connected to the calculation section. Difference Engine 1 is the first complete design for automatic calculation.
From time to time Babbage changed the functionality of the device. An 1830 design depicts a machine designed for 16 digits and 6 orders of difference. The model consisted of 25 thousand parts, divided equally between the computing section and the printer. Had the device been built, it would have weighed an estimated 4 tons and be 2.4 meters high. Work on Babbage's Difference Engine was h alted in 1832 after a dispute with engineer Joseph Clement. Government funding finally ended in 1842
Analytical Engine
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 Engine. The structural properties of Babbage's machine largely correspond to the basic building blocks of a modern digital computer. Programming is done using punched cards. This idea was taken from the jacquard loom, where they are used to create complex textile patterns.
The logical structure of Babbage's Analytical Engine basically corresponds to the dominant design of computers of the electronic age, which implies the presence of memory ("store"), separated from the central processing unit ("mill"), sequential execution of operations and facilities for input and output of 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 is performed. She had a set of 4 arithmetic functions and could perform direct multiplication and division. In addition, the device was capable of performing operations that are now called conditional branching, loop (iteration), microprogramming, parallel processing, fixing, pulse shaping, etc. The author himself did not use such terminology.
The CPU of Charles Babbage's Analytical Engine, which he called the "mill", provides:
- storage of numbers, operations on which are performed immediately, in registers;
- has the hardware to perform basic arithmetic operations on them;
- transferring user-oriented external instructions to detailed internal control;
- timing system (clock) for executing instructions in a carefully selected sequence.
The control mechanism of the analytical engine performs operations automatically and consists of two parts: a lower level controlled by massive drums called barrels, and a high level using punched cards designed by Jacquard for looms widely used in the early 1800s.
Output devices
The result of calculations is displayed in a variety of ways, including printing, punched cards, plotting, andautomatic production of stereotypes - soft material trays on which the result is imprinted, capable of serving as a mold for casting plates for printing.
New design
Babbage's pioneering work on the Analytical Engine was largely completed by 1840 and began to develop a new device. Between 1847 and 1849, he completed the development of Difference Engine No. 2, which was an improved version of the original. This modification was designed for operations with 31-bit numbers and could tabulate any polynomial of the 7th order. The design was exquisitely simple, requiring only a third of the original model's part count, while providing equal processing power.
The difference and analytical engines of Charles Babbage used the same design of the output device, which not only made printouts on paper, but also automatically created stereotypes and independently performed formatting according to the page layout specified by the operator. At the same time, it was possible to adjust the line height, number of columns, field widths, automatic folding of rows or columns and arrangement of empty lines for readability.
Legacy
Apart from a few partially created mechanical assemblies and test models of small working sections, none of the designs were fully realized during Babbage's lifetime. The main model assembled in 1832 was 1/7 of Difference Engine No. 1, which consisted offrom about 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 while the small experimental part of the Analytical Engine was being assembled. Many details of the construction have been preserved, as well as a complete archive of drawings and notes.
Babbage's designs for huge mechanical computers are considered one of the stunning intellectual achievements of the 19th century. It is only in recent decades that his work has been studied in detail, and the importance of what he has done is becoming increasingly clear.
