a computer in which the initial data and the programs for each operation are introduced manually on a keyboard. Keyboard computers are the most widespread modern equipment for mechanization of calculations and computational operations; they are designed for small engineering and mathematical computations, as well as for economic, statistical, and accountancy work. Keyboard computers are divided into three groups: calculators, adding machines, and tabulators. Strictly speaking, keyboard computers include machines designed to perform all four arithmetical operations, but above all efficient multiplication and division.
According to the degree to which the computing process is automated, keyboard computers are subdivided into the simplest, nonautomatic types, in which all operations are performed manually, such as the VK-1 (USSR); the semiautomatic type, which has an actuator that performs only one operation automatically, such as division in the VK-2 and VMP-2 (USSR) and the Soemtron-210 (German Democratic Republic); and the automatic type, in which the only manual operations are the selection of the basic data and the start of the machine, such as the VK-3 and VMM-3 (USSR) and the Soemtron-215 and Cellatron (German Democratic Republic). Of particular note among such computers are the relay and electronic machines, which have almost no mechanical kinematic linkages but have a number of new operational capabilities with respect to speed of operation, input and output of data, operations, and program control units. Among them are the Viatka, Vil’nius, and Vega (USSR); the Soemtron-220 and Soemtron-221 (German Democratic Republic); and the Elka (Bulgaria). Keyboard computers are also distinguished with regard to the number of available counters and by their clocking period, modularity concepts, and type of actuator.
A main part of a keyboard computer is the counter, which performs the same functions in all computers of this type—the digit-by-digit addition of the input numbers and the transfer of a ten accumulated in one stage to the next higher stage. The initial data and the type of operation are introduced into the machine by pressing the corresponding keys. According to the type of input arrangement, a distinction is made between single-digit (ten-key or ten-lever) and multidigit (multilever and multikey) types of keyboard computers. The input information is recorded in the machine by a change in the position or physical state of its parts (elements). For example, in electromechanical keyboard computers a “1” is recorded by rotation of the “counting pinions” through an angle of 36°; one-digit numbers are added in this manner. For a complete rotation, which corresponds to a count of 10, the tens are transferred to the next higher place by rotating the adjacent pinion of the higher place through 36° (“1”). Multiplication is accomplished by successive digit-by-digit addition of the multiplicand; division, by successive digit-by-digit subtraction of the divisor from the dividend.
The current classification of keyboard computers according to the attributes mentioned above is somewhat arbitrary, since there are machines in widespread use that are hard to classify. In addition to manual keyboard input, the most advanced computers have punched-card and perforated-tape input and output, which makes possible automatic introduction of tabulated data, constants, and standards, thus substantially improving their throughput capacity. The use of subassemblies and elements from electronic computers in keyboard computers has essentially not only altered the principles of their design but also promoted the development and extension of new service potential.
REFERENCESRiazankin, V. N., G. P. Evstigneev, and N. N. Tresviatskii. Vychislitel’nye mashiny, part 1. Moscow, 1957.
Usan, A. M. Schetno-klavishye mashiny. Moscow, 1967.
Vychislitel’nye mashiny i programmirovanie. Moscow, 1970.
V. P. ISAEV