JPH0248760A - Method for accessing peripheral device - Google Patents

Abstract

PURPOSE:To effectively use waiting time so as to reciprocate a control signal to/from other peripheral device by accessing the started peripheral device for next processing after waiting for prescribed time required till the next processing becomes executable. CONSTITUTION:An I/O bus adapter 22 corresponds to an interface device to monitor a processing state at each of plural peripheral devices and mediate an instruction from a central processing unit for each of plural peripheral devices,and a pair of an I/O 23 and an external device 24 and a pair of the I/O adapter 25 and the external device 26 correspond to the respective peripheral devices. Then, the interface device accesses the peripheral device after it waits for each peripheral device for prescribed time till the peripheral device becomes capable of executing the next processing, and during the period, it does not access the peripheral device. Thus, the interface device can reciprocate the control signal to/from other peripheral device by using the control line of a bus during the waiting time.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a peripheral device access method using an interface device that monitors the processing status of each of a plurality of peripheral devices and mediates commands from a central processing unit to each of the plurality of peripheral devices. , Even while the interface device waits for the peripheral device to be released from the busy state, the bus control line can be effectively used for the exchange of control signals by the interface device with other peripheral devices. A central processing unit, a plurality of peripheral devices that execute processing according to instructions from the central processing unit, and monitoring the processing status of each of the plurality of peripheral devices, A peripheral device access method using an interface device that mediates commands to each of the peripheral devices, wherein the interface device activates each peripheral device by giving a command issued from the central processing unit. Sometimes, after the activation is applied, the peripheral device that activated the activation performs processing corresponding to the activation and waits for a predetermined time required for the next process to be executed, and then the peripheral device that activated the activation is activated. The configuration is such that access is performed for the next process.

[Industrial application field]

The present invention relates to a peripheral device access method using an interface device that monitors the processing status of each of a plurality of peripheral devices and mediates commands from a central processing unit to each of the plurality of peripheral devices.

In a computer system to which a large number of peripheral devices are connected, the central processing unit (CP U) and the plurality of peripheral devices, the peripheral device has a function of monitoring the processing status of each of the plurality of peripheral devices and mediating commands from the central processing unit to each of the peripheral devices, and Some interface devices are provided with a plurality of subchannels corresponding to each of the subchannels.

Additionally, due to demands for cost reduction, peripheral devices connected to the above-mentioned interface devices do not have an interrupt function for the central processing unit (CPU), and simply interrupt the CPU in a busy state. There are some that only have a flag indicating whether or not they are accepted.

For such peripheral devices, the above-mentioned interface device mediates instructions from the central processing unit (CPU),
When a predetermined operation is activated, the peripheral device executes processing in response to the activation command, and during this processing, the peripheral device is in a busy state.

In contrast, conventionally, the interface device repeatedly attempts to access the peripheral device until the busy state in the peripheral device is released, and when the busy state is released, the interface device issues a command to start the next operation. was giving.

However, if the interface device repeatedly tries to access one peripheral device until the busy state is released, the bus control line will continue to be monopolized during this time, and other interface devices will This will impede the exchange of control signals with other peripheral devices through the subchannel corresponding to that peripheral device.

Therefore, there has been a demand for technology that can solve these problems.

[Prior art and problems to be solved by the invention]

FIG. 3 shows the procedure of a conventional access method for a peripheral device using an interface device.

In FIG. 3, after the interface device activates the peripheral device in step 31, while the peripheral device is executing the corresponding process, the peripheral device cannot accept activation of the next process. Unable to do so, flag it as busy. During this time, as shown in step 32, the interface device repeatedly attempts to access the peripheral device in order to initiate the next operation.

When the above processing in the peripheral device is completed and the busy state is released, in step 33, the peripheral device is activated for the next operation.

In this way, while the interface device repeatedly tries to access one peripheral device until the busy state is released, the bus control line continues to be monopolized, and the interface device's other peripheral devices There was a problem in that control signals could not be exchanged smoothly with other peripheral devices through the five-channel network.

The present invention has been made in view of the above problems, and includes an interface device that monitors the processing status of each of a plurality of peripheral devices and mediates commands from a central processing unit to each of the plurality of peripheral devices. While waiting for the device to clear the busy state, the control lines of the bus can be effectively used for exchanging control signals with other peripheral devices through subchannels corresponding to other peripheral devices of the interface device. The object of the present invention is to provide a method for accessing peripheral devices.

[Means to solve the problem]

In the peripheral device access method of the present invention, the interface device, which monitors the processing status of each of the plurality of peripheral devices and mediates commands from the central processing unit to each of the plurality of peripheral devices, provides a When the peripheral device is activated by giving a command issued from the central processing unit, after the activation is performed, the peripheral device that has been activated performs the process corresponding to the command, and the next process can be executed. After waiting for a predetermined period of time, the activated peripheral device is accessed for processing.

[For production]

According to the peripheral device access method of the present invention, the interface device waits a predetermined period of time for each peripheral device until the peripheral device can execute the next process, and then provides an access method for the next process. During the access, the peripheral device is not accessed. Therefore, during the above waiting time, the interface device can exchange control signals with other peripheral devices using the bus control line.

〔Example〕

FIG. 2 is a schematic configuration diagram of a computer system to which the present invention is applied.

In FIG. 2, 11 is a CPU, 22 is an I10 bus adapter, 23.25 is an I10 adapter, and 24.262 are external devices connected to the I10 adapter 2325, respectively.

The above-mentioned I10 bus adapter 20 corresponds to the above-mentioned interface device that monitors the processing status of each of the plurality of peripheral devices and mediates commands from the central processing unit to each of the plurality of peripheral devices. 23 and external device 24, and I10 adapter 25 and external device 2
6 correspond to the aforementioned peripheral devices, respectively.

The external devices 24 and 26 mentioned above are, for example, data output devices such as printer devices and display devices, or data input devices such as keyboard devices.

FIG. 1 shows the procedure of the peripheral device access method of the present invention.

In FIG. 1, after the interface device activates the peripheral device in step 11, while the peripheral device is executing the corresponding process, the peripheral device cannot accept activation of the next process. Unable to do so, flag it as busy. During this time, as shown in step 12, the interface device waits for a predetermined period of time required for the activated peripheral device to perform processing corresponding to the instruction and to be able to execute the next processing. This waiting time should be set to an appropriate time by examining the characteristics of each peripheral device in advance.
Although not shown, this time waiting can be realized by providing a timer circuit for each peripheral device in the interface device.

Then, after the above predetermined waiting time has elapsed, step 1
At step 3, check that the peripheral is not already busy. From the procedure for setting the waiting time described above, at this time,
The peripheral should already be not busy, but if
Here, if the peripheral device is still busy, it is determined that some abnormality has occurred (an error).

If the peripheral device has been released from the busy state in step 13, then in step 14 the peripheral device is activated for the next operation.

As described above, according to the procedure of the present invention, the above-mentioned interface device does not repeatedly try to access until the busy state in one peripheral device or a device is released, so that the bus control line is connected to the interface device. The exchange of control signals in a device with other peripheral devices or adapter devices by means of subchannels corresponding to other peripheral devices of the interface device that no longer remain occupied by subchannels corresponding to one peripheral device; can be done smoothly.

〔Effect of the invention〕

According to the peripheral device access method of the present invention, the interface device that monitors the processing status of each of the plurality of peripheral devices and mediates commands from the central processing unit to each of the plurality of peripheral devices, While waiting for the condition to clear, the control lines of the bus can still be effectively used for exchanging control signals with other peripherals via subchannels corresponding to the other peripherals of the interface device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the procedure of the peripheral device access method of the present invention, FIG. 2 is a schematic configuration diagram of a system to which the present invention is applied, and FIG. 3 is a diagram showing the procedure of the conventional peripheral device access method. It is a diagram. [Explanation of symbols] 11...CPU. 22... Bow 10 bus adapter, 23. 25... I/○ adapter, 24° 262... External device.

Claims (1)

[Claims] 1. Central processing unit (21); and the central processing unit (21)
Multiple peripheral devices (2
3, 25) and the processing status of each of the plurality of peripheral devices (23, 25), and mediates instructions from the central processing unit (21) to each of the plurality of peripheral devices (23, 25). A method for accessing a peripheral device by an interface device (22), wherein the interface device (22)
, 25) is activated by giving a command issued from the central processing unit (21), after the activation, the peripheral device to which the activation was applied performs processing corresponding to the command. 1. A method for accessing a peripheral device, comprising: waiting a predetermined time required for the next process to become executable, and then accessing the activated peripheral device for the next process.