JPH02211568A - Bus control system - Google Patents

Abstract

PURPOSE:To execute the selection of a transfer destination device without delay by providing an ID sending-out means, a control means for selecting the other party and a means for controlling the inhibition of sending out an ID on a bus controller in a data transfer device. CONSTITUTION:Devices I1, I2 select devices T3 - T5 as the other parties. The devices are provided with a control part 1 for executing a selection of two pieces of buses, a check of a use state and a data transfer control to an external super-ordinate or subordinate device, an SCSI control part 2 for controlling to supply and receive information to and from buses L1, L2, a control part 3 for controlling an interface to an external device, and a circuit for utilizing an unused bus and sending an ID, respectively. By such constitution, an unselected device is set as the other party by using an unused bus and data is sent, and an ID of the device which is transferring the data is sent to the other unused bus. The other device decides whether the other party is transferring the data or not, based on the ID. In the case of being in the course of transfer, the bus use is suspended without selecting this device. In the case of being in the course of non-transfer, this device is selected and it is stopped to sending out the ID, and the data is sent. Accordingly, a transfer destination device is selected without a delay.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to the field of information processing technology. In particular, S
CS I (Small Computer System)
EM Interface) bus control system.

〔overview〕

In a control method for two buses in which two sets of devices transfer data, the present invention enables the transmission of an identifier that identifies the device currently transferring data to the bus on which data transfer is not being performed. This makes it possible to shorten the time required to confirm the bus usage status.

[Conventional technology]

Conventionally, there is no way to directly know which device is using the 5csr bus, and based on the SC5I procedure, the unused bus of the two buses is used to select the other device.
It detected that the other party was not responding because the bus was in use, and checked the device that was using the bus.

[Problem that the invention seeks to solve]

In this way, in the conventional technology, the other device is notified of the intention to select based on the original SCSI procedure, and the bus usage status of the other device is checked based on whether or not there is a response from the other device. This has the disadvantage that the bus is monopolized for more than a specified time to check the response of the other device, and if the other device cannot be selected, the processing capacity of the entire system will be significantly reduced. be.

SUMMARY OF THE INVENTION The present invention aims to eliminate such drawbacks and to provide a bus control method that allows selection of a data transfer destination device without delay.

[Means for Solving the Problems] The present invention provides two buses and a plurality of devices connected to each of the buses and having selection means for selecting a partner device to which data is transferred based on the SCS R procedure. In the bus control method, each of the above devices includes an identifier for identifying each of the devices selected by the selection device on a bus to which a device not selected by the selection device is connected. An identifier sending means for sending information, a specifying means for specifying a device that has not been selected by the selecting means based on the identification information, and a device specified by the specifying means is permitted to be selected as a partner device. a first control means for giving a command to the selection means; and a first control means for prohibiting the sending of the identification information from the identifier sending means when the selection means makes a selection via the bus through which the identification information is sent. It is characterized by having two control means.

[Effect]

Data is transferred to an unselected device via an unused bus. Sends identification information identifying the device transferring data to another unused bus. Next, the other device determines whether the partner device to which data is to be transferred is the device currently transferring data, based on the identification information. If the other device is transferring data, use of the bus is stopped without selecting this device. Also, if the other device is not transferring data,
This device is selected, transmission of identification information is stopped, and data transfer is performed.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. 1st
The figure is a block configuration diagram showing the configuration of this embodiment.

In this embodiment, as shown in FIG. 1, devices 11 and I2 on the side that select the other device based on SCSI regulations,
A device T3 on the side selected by the other party device based on the same provision,
I4 and I5, and buses L1' and L2 used for data transfer between devices.

Further, FIG. 2 is a block diagram showing the configuration of the devices 11 to I5 shown in FIG. 1. As shown in FIG. 2, each of the devices 11 to I5 includes a control unit 1 that controls the selection of two buses, checking the usage status, and data transfer with an external device (upper or lower device), and a bus L1. and L2, an external interface controller 3 that controls the interface with an external device, and an I that sends out an ID using an unused bus.
It is composed of a D sending circuit 4.

That is, in this embodiment, as shown in FIGS. 1 and 2, two buses Ll and L2;
SC, which is a selection means for selecting a partner device connected to each of the
A plurality of devices 11, I2, I3, I having an SI control unit 2
4 and I5, and each of the devices 11, I2, I3, I4, and I5 is a device selected by the selection device to a bus to which a device not selected by the selection device is connected. an ID sending circuit 4 which is an identifier sending means for sending out identification information for identifying each of the devices; a specifying means for specifying a device that has not been selected by the selecting means based on this identification information; When selection is made by the self-selecting means via the first control means for giving a command to the selection means to permit selection of the device as a partner device and the bus to which this identification information is sent, the above-mentioned identifier and a second control means for prohibiting the transmission of the identification information from the transmission means.
and has.

In the present invention, a "bus not in use" refers to a state in which all devices connected to the bus are not sending control signals for SCSI control onto the bus. Here, the ID is not a control signal.

Next, the operation of this embodiment will be explained based on FIGS. 1 and 2. The control unit 1 in the device Il checks buses L1 and L2 before data transfer with the device T3, and
device T using this bus L1 when l is unused.
Select 3. Having recognized that its own device has been selected, the control section 1 in the device I3 returns a response to notify the device 11 that its own device, which is not currently using the bus, has been selected. Subsequently, data is transferred between device 11 and device T3 using bus L1. At this time, the IDs of the device 11 and the device T3 using the bus Ll are sent onto the unused bus 2. Next, when the control unit I in the device I2 checks buses Ll and L2 before using either of the buses L1 and L2, bus L1 is in use, and when it subsequently checks bus L2, bus L2 is unused. Therefore, the control unit 1 in the device I2 checks the ID sent on the bus 2 and detects that the devices using the bus L1 are the device 11 and the device T3. At this point, the device using bus L1 has been recognized, so if the other device to which you tried to transfer data using bus L2 is a device using bus L1, the original procedure will be resumed. Based on this, the use of the bus is stopped without attempting to select the other device using the bus Ll. Therefore, bus L2 remains unused.

However, if the other device is not currently using the bus L1, the selection is possible, and the controller l in the device I2 is connected to the bus L2.
to the other device (in this case, device T4 or I5)
). When device I2 starts using bus L2, ID sending circuits 4 in devices 11 and I3 use bus L2.
It detects that the ID is in use and stops sending out each ID that was being sent out on the bus I2. Furthermore, when the bus L1 that has been in use is finished, the bus L2 is placed on the bus Ll.
The ID of the device currently using is sent.

〔Effect of the invention〕

As explained above, the present invention is capable of recognizing the bus usage status of the other device that the device is trying to select without executing the original procedure, so the device executes the procedure, performs the selection operation, and determines whether or not there is a response. This has the effect of saving you from spending more time than the specified time to do so. Furthermore, even if one bus is in use, data can be transferred between devices in parallel using the other unused bus, so an efficient SCSI system can be constructed.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing the configuration of an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of the apparatus shown in FIG. 1. 1112, I3, I4, I5...device, Ll, L2・
...Bus, 1...Control unit, 2...SCSI control unit,
3... External interface control section, 4... ID sending circuit. Configuration diagram of the embodiment diagram C3I Configuration diagram of the interface use device

Claims (1)

[Claims] 1. Two buses, and selection means for selecting a partner device connected to each of the buses and to which data transfer is to be performed based on the SCSI procedure.
2), in which each of the above devices is selected by the selection means on a bus connected to a device that has not been selected by the selection means. an identifier sending means (4) for sending out identification information for identifying each of the devices; a specifying means for specifying a device that has not been selected by the selecting means based on this identification information; and a device specified by the specifying means. a first control means for giving a command to the selection means to permit selection of the device as a partner device; and, when the selection by the selection means is made via the bus to which this identification information is sent, the identifier sending means; and second control means for prohibiting transmission of identification information from the bus.