SU807296A1 - Two-input priority device - Google Patents

Description

(54) PRIORITY TWO-INPUT DEVICE

one

The invention relates to the field of computer technology, in particular, to devices of priority and can be used for which to reach out from two subscribers to a common resource.

A prioritization device is known, which contains triggers, AND elements and OR elements, which allow switching input signals from various sources of information to the output of the bus l.

However, such a device is distinguished by its complexity and limited scope when sampling channel input signals.

It is also known that a priority device containing triggers, elements OR and OR-NOT, allows the xchzee to switch input signals (applications) coming from different channels, to the corresponding output buses. In this case, a request with a lower number is given a priority in service 2 j.

However, this device also does not have an extended scope when sampling readiness signals from channels. So, for example, if during control, by retrieving information from a channel with a lower priority, the ready signal from will be sent to the input of this device. a channel with a higher priority, the control signal of the availability of the channel with a lower priority is interrupted, and this can lead to distortion of the transmitted information and failure of the device.

0

. The closest in technical essence to the present invention is a two-input priority device containing AND elements, a trigger, a delay element, an NO element, and an element

5 OR NOT.

The operation of this unit is based on the principle of automatic switching of signals arriving at the inputs of the unit from two different sources.

0 information on one of the outputs of the block depending on the time of their occurrence. When signals from different sources appear simultaneously, the first of these takes precedence over

5 corresponding to the output of the unit C,. A disadvantage of the known device is an increase in the cost of the equipment, as well as the impossibility of ensuring the translation of the ready signal present on one of its inputs to the corresponding output of the roll after removing (testing) a similar signal from another source. ka information. For example, when the input signal at the second input of the first element AND (the first input of the device) disappears, the trigger does not switch to the initial (zero) state, because at this time its potential at the steering input is low. the first input of the element OR NOT (second input of the device) of the input signal of positive polarity. Since the trigger does not switch to the initial state, a low potential level continues to be present at its inverse output, which, acting on the first input of the second element I, blocks the passage of the corresponding signal from the second source of information through the negon of the corresponding lines. Thus, the use of this device is possible only in those systems in which in the process of transmitting a ready signal from one information source (channel). A similar signal at the device input from another channel should be absent and appear on it only after it has been lost (working ) the specified signal from the channel. In this case, the trigger is switched to the initial (zero) state by a signal of positive polarity, produced at the output of the OR-NOT element. All this limits the scope of application of a known device, since in practice there are often situations when it becomes necessary to receive information from two autonomous devices in accordance with the chosen priority. At the same time, each information word is accompanied by a readiness signal, by means of which information is received from an external source. In addition, the known device does not provide the necessary switching of input signals in the event of their simultaneous appearance from sources of information after testing the delay element, which also reduces its functional capabilities. The purpose of the invention is to reduce equipment and expand functionality by eliminating restrictions on the moments of receipt of requests. The goal is achieved by the fact that a two-input priority device containing the first element AND, the output of which is connected to the trigger input, the second element AND, the first input of which is connected to the inverse output of the trigger, the element NOT and the delay element. moreover, the first input of the first element I, the direct output of the trigger and the output of the second element I are the first input and the first, second output of the device, respectively, an additional element is NOT, and the output of the first element I is NOT connected to the extinguishing trigger input, the output of the second element And through the element is NOT connected to the second input of the first element And, and the second input of the device through the delay element - to the second input of the second element I. The drawing shows the block diagram of the device. The two-input priority device contains delay element 1, element NOT 2, trigger 3, elements AND 4 and 5, input 6, output 7, additional element NO 8, output 9, input 1o. The device works as follows. The initial state is characterized by the absence of signals at inputs 6 and ip. At the same time, trigger 3 is in the zero state, since at its zero input there is a high potential level, and at its single input there is a low potential level i aina. At the outputs 7 and 9 there are low potential levels, i.e. output signals are also missing. The device is in the waiting mode for the arrival of input signals and is ready for their switching to the corresponding outputs. Input signals from information channels may appear at different times relative to each other. Consider the operation of the device while simultaneously receiving readiness signals through channels connected to inputs 6 and 10. In this case, at the output of element 4, the low potential level changes to high, and on the output of the element 8, the high potential level changes to low. As a result, the trigger 3 switches to one state and at its direct output (device output 7) appears, a high potential level, (positive signal), and at its inverse output a low potential level. Low potential. from the inverse trigger output acts on the first input of the element 5 and blocks the passage of the readiness signal through it, which arrives at the second input of the specified element from the second channel after testing the delay element 1. Thus, with simultaneous receipt of ready signals from two channels, the priority of the broadcast of the specified signal from the first channel to the first output 7 is provided. If the priority channel fails when the device is used for

Claims (1)

Claim A two-input priority device containing the first element And, the output of which is connected to the trigger installation input, the second element And, the first input of which is connected to the inverse trigger output, the NOT element and the delay element, the first input of the first And element, the direct output of the trigger and the output of the second Element And they are respectively the first input and the first, second outputs of the device, characterized in that, in order to reduce equipment and expand functionality by eliminating restrictions on the moments of arrival query, it contains an additional element NOT, and the output of the first element AND through the additional element is NOT connected to the extinguishing input of the trigger, the output of the second element AND through the element is NOT connected to the second input of the first element AND, and the second input of the device through the delay element 30 second the input of the second element I.