JPH0328951A - Input/output controller - Google Patents

Abstract

PURPOSE:To improve the using efficiency of a common bus by attaining the direct comparison between the running level of a CPU and its own interruption level and preventing the occurrence of an invalid interruption to the CPU. CONSTITUTION:An interruption level deciding circuit 114 fetches the running level of a CPU 102 outputted to a common bus 101 via a running level monitor circuit 113. Then the circuit 114 compares the running level of the CPU 102 with its own interruption level. If the interruption level has its priority higher than the running level, the circuit 114 grants the execution of an interruption to an interruption circuit 112. While the execution of the interruption is held if the priority of the interruption level is lower than the running level. Then an input/output controller 100 holds the interruption until the priority of the running level becomes lower than the interruption level. As a result, no invalid interruption is produced to the CPU 102 and the using efficiency of the bus 10 is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an input/output control device for a data processing system, and more particularly to an input/output control device that generates an interrupt to a central processing unit. Conventional technology Conventionally, in this type of input/output control device, when generating an interrupt to the central processing unit, the input/output control device did not compare the interrupt level with the running level of the central processing unit. ．． When an interrupt factor occurs, the input/output control unit issues an interrupt to the central processing unit regardless of the state of the central processing unit. The central processing unit compares the interrupt level with its own level and determines whether the interrupt can be accepted or not. The central processing unit then notifies the input/output control unit whether or not the interrupt has been accepted. Problems to be Solved by the Invention In the conventional input/output control device described above, an interrupt occurs even if the running level of the central processing unit has a higher priority than the interrupt level. As a result, unnecessary bus transfers occur on the common bus, reducing the efficiency of using the common bus. The present invention has been made in view of the above-mentioned conventional circumstances, and therefore, an object of the present invention is to solve the above-mentioned problems inherent in the conventional technology, suppress the occurrence of invalid interrupts to the central processing unit, The purpose of this project is to provide a new input/output control device that makes it possible to improve the efficiency of using a common bus. Means for Solving the Problems In order to achieve the above object, an input/output control device according to the present invention includes a driving level monitoring circuit that inputs the driving level of the central processing unit from a dedicated line of a common bus, and a driving level monitoring circuit that inputs the driving level of the central processing unit from a dedicated line of a common bus. It is configured with an interrupt level determination circuit that compares the interrupt level assigned in advance to the own device and determines whether or not an interrupt is allowed, and an interrupt circuit that generates an interrupt to the central processing unit. The feature is that an interrupt is executed only when the level has a lower priority than its own interrupt level. Embodiment Next, a preferred embodiment of the present invention will be specifically explained with reference to the drawings. FIG. 1 is a block elliptical diagram showing one embodiment of the present invention. Referring to FIG. 1, an input/output control device 10 according to the present invention
0 is connected to the central processing unit 102 via a common bus 101. When an interrupt factor occurs in the input/output control device 100, the main control circuit 111 activates the interrupt to the interrupt circuit 112, and requests the interrupt level determination circuit 114 to determine whether or not the interrupt is allowed. The interrupt level determination circuit 114 is connected to the running level monitoring circuit 1.
13, the running level output from the central processing unit 102 to the common bus 101 is taken in and compared with its own interrupt level. As a result of the comparison, if the interrupt level has higher priority than the running level, the interrupt level determination circuit 11
4 permits the interrupt circuit 112 to execute an interrupt. An interrupt circuit 112 controls the bus interface circuit 110 to generate an interrupt to the central processing unit 102. If the comparison result of the interrupt level determining circuit 114 indicates that the interrupt level has a lower priority than the running level, the interrupt level determining circuit 114 instructs the interrupt circuit 112 to suspend execution of the interrupt. In this case, the central processing unit 102 changes the driving level, and the input/output control unit 102 changes the driving level.
The input/output control device 100 suspends interrupts until the running level becomes lower than the interrupt level of . In addition, if the running level was low at the time when the interrupt level determination circuit 114 judged whether or not the interrupt was possible, but the running level was changed at the time when the interrupt occurred and the priority became higher than the interrupt level, the central processing The device 102 rejects the interrupt and notifies the input/output control device 100 accordingly. The input/output VI control device 100 that receives the rejection notification suspends the interrupt, and suspends the interrupt when the running level of the central processing unit 102 becomes lower than the interrupt level again. Effects of the Invention As explained above, according to the present invention, invalid interrupts to the central processing unit can be prevented by allowing the input/output control unit to directly compare the running level of the central processing unit with its own interrupt level. This has the effect of suppressing this occurrence and improving the efficiency of common bus usage.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of an input/output control device according to the present invention. 100... Input/output control device, 101... Common bus,
102... Central processing unit, 110... Bus interface circuit, 111... Main control circuit, 112... Interrupt circuit, 113... Driving level monitoring circuit, 114...
・Interrupt level determination circuit

Claims (1)

[Claims] In an input/output control device that is connected to a central processing unit via a common bus and generates interrupts to the central processing unit,
An interrupt circuit for generating an interrupt to the central processing unit, a running level monitoring circuit that inputs the running level of the central processing unit from a dedicated line of the common bus, and an interrupt that is pre-assigned to the running level and the own device. An input/output device characterized in that it has an interrupt level determination circuit that compares the interrupt level with the interrupt level and determines whether or not an interrupt is allowed, and executes the interrupt only when the running level of the central processing unit has a lower priority than its own interrupt level. Control device.