SU750492A1 - Device for minimizing logic functions - Google Patents

Description

one

The invention relates to automation and computing and can be used in the synthesis of logic devices.

A device for minimizing the structure of logic circuits is known, comprising a decoder, a digital dial board, indication lamps, keys Ij.

The disadvantage of the device is a large amount of equipment.

The closest technical solution to this invention is a device for minimizing the structures of logic functions, comprising a control unit, a decoder, a logic unit, a register, a dial-in field, indication and recording units, the input of the logic unit is connected to the decoder, and the output is , the keypad is connected two-way with the decoder, the first input and output of the control unit are connected to the logic unit, the second output of the control unit is connected to the logic unit

and the decoder, and the third through the register - / to logic unit 2.

The known device uses the minimization algorithm, based on the selection of all simple imlicant of a Boolean function, which requires a large number. computing and hardware costs.

The well-known method of simplifying Boolean functions, proposed by V. P. Didenko, does not require the isolation of all simple implicants and allows one to obtain simplified expressions in a smaller number of operations. The method consists in extracting mandatory letters in sets of a Boolean function and composing from them essential simple implicants.

An optional letter in the working set (och,...,, 1 ,,,.,., SI) on which the Boolean function f (X, -., 20) 1 is called the letter X-,,: if the set Р С, -, Х.; ,, О, 0 (,, ..), adjacent to the set of h in the variable Kj,. is a non-working set, i.e. on it the function () is equal to O.

In practice, when minimizing the Boolean function, the selection of the required letters in its sets is performed alternately by deleting the columns of the table TOHHHif for each of the variables.

The purpose of the invention is to simplify the device and increase speed.

This goal is achieved by the fact that the first inputs of the display elements of the i-th row of the matrix. (1 4 2) are connected to the positive terminal of the power supply unit through the disconnecting contacts of the -th switch, and to the negative terminal of the power source through the closing contacts, the second inputs are the display elements of the first column matrix (1, 3, 5, .... 2 - 1) connected to the second inputs. To the display elements of the zero-stage matrix {to 2, 4, 6, ... . , 2), the second inputs of the инди-th elements of the matrix display of the j-th column (E - 1, 2,.

jj-vl

2J, 1, 2

22J -2-1

+ 2,

C- ™ -, (j -2, 3, ..., p) are connected to the second inputs of the k-th display elements of the matrix of the j-th column. The drawing shows a diagram of the device, where 1-64 elements of the display matrix, 65-89 switches. The underlined digit above each display element indicates the value of the dialing variable corresponding to this element. The position of the switch 65, in which the terminal + of the power supply is connected to the display elements of this set, corresponds to the fact that the given Boolean function on this set takes a value of 1, and the position of the switch O, which connects to the dial display elements from the terminal - corresponds to that a given Boolean function on this set takes a value equal to 0. The operation of the device is illustrated by the example of highlighting the required letters in the function sets defined by the truth table.

The continuation of the table. The switches 65 - 80 corresponding to the single sets of the given Boolean function are set to position 1, while the terminal + of the power supply is connected to the display elements with decimal numbers 1, 5, 6, 7, 9, 11, 12, 15, and the source terminal is for the display elements with the numbers O, 2, 3, 4, 8, 10, 13 and 14. As the display elements in the variable K column are connected in the following pairs (see drawing); 1-33, 5-37, 9-41, 13-45, 17-49, 21-53, 25-57, 29-61, then the display elements are connected by pairs of 2-18, 6-22, 10-26, 14-ZO, 34-50, 38-54, 42-58,. Therefore, the display elements 1О, 14, 26, 30, 34, 38, 50, 54 work. In the variable X column, the display elements are connected by the following pairs: 3-11, 7-15, 19-27, 23-31, 35-43, 51-59, 55-63, therefore, the following display elements 7, 15, 19, 27, 51, 55, 59, 63 work. In the variable X column, the display elements are connected in pairs 4-8, 12-16, 20-24, 28 -32, 36-40, 44-48, 52-56, 60-64, therefore, the display elements 4, 8, 20, 24, 36, 4О, 44, 48, 52, 56, 6О, 64 work. Thus, both in the sets, on which the function is equal to 1, and in the sets, on which the function is equal to O, the obligatory and termized ones, outlined in the table, are muddy circles. When specifying a Boolean function in the form of a disjunctive normal form (DNF), it is necessary to set in 1 those switches whose sets are covered by the DNF members.

If the number of variables of a given function is less than the number of variables for which the device is designed, then when selecting the required letters, it is not necessary to use the corresponding truncated part of the device.

The selection of the required letters in sets of different Boolean functions takes the same time, and the result is obtained almost immediately after setting the function by setting the dial switches.

Claims (1)

1. USSR author's certificate number 177692, cl. G- About F- 15/34, 1966, 0 2V USSR Author's Certificate No. 428387, cl. G 06 F 15/34, 1974 ,. (prototype).