JPH03278155A - Scsi bus extending circuit - Google Patents

Abstract

PURPOSE:To extend the number of initiator devices which can be connected by providing at least one of initiator circuit and SCSI bus control circuit. CONSTITUTION:Personal computers 1 - 3 being initiator devices are connected to an SCSI bus extending circuit 5 through an SCSI (Small Computer Systems Interface) bus 4, and a hard disk drive controller 6 being a target device is connected to the SCSI bus extending circuit 5 through an SCSI bus 7. Also, to the SCSI bus 7, personal computers 8 - 13 being initiator device are connected, and to the hard disk drive controller 6, a hard disk drive 14 is connected. In such a way, the initiator devices which can be connected can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a 5C3I bus expansion circuit, and particularly to a SCSI bus expansion circuit that can expand the number of initiator devices that can be connected to a SCSI bus.

[Conventional technology]

Most workstations are equipped with floppy disk drives and hard disk drives, and these devices are rapidly becoming smaller and larger in capacity. SCSI is the standard interface for connecting these hard disk devices and the main unit.
(Small Computer SystemsIn
(interface) bus is the mainstream.

The third example of reading data on the conventional 5C3I bus
This will be explained based on the diagram. FIG. 3 is a system configuration diagram showing the operation of a conventional 5C3I bus. Figure 3 shows that seven personal computers 8 to 13 as initiator devices are SCSI
A hard disk drive controller 6 as a target device is connected to the SC3I bus 7, and a hard disk drive 14 is connected to the hard disk drive controller 6. Third
(IDI), (ID2), etc. shown in parentheses in the figure are 5C3
This is an ID number as an identification number of each initiator device and target device when connected to the I bus 7.

Now, the personal computer 8 wins the arbitration for the right to use the SCSI bus 7 and selects the hard disk drive controller 6 as the target device. Data transfer between the personal computer 8 and the hard disk drive controller 6 is now possible. Next, the hard disk drive controller 6 issues a signal to the personal computer 8 to request a data read command. In response, the personal computer 8 sends a data read command to the hard disk drive controller 6. Next, the hard disk drive controller 6 sends the data in the hard disk drive 14 to the personal computer 8. When the data has been sent, the hard disk drive controller 6 reports the status of the command execution result to the personal computer 8, sends a command completion message, and the reading ends.

[Problem to be solved by the invention]

In the conventional SCSI bus operation configuration described above, 5
Since the number of devices that can be connected to the C3I bus is limited to eight, including the initiator device and target device, there is a drawback that if one hard disk drive controller is connected, only up to seven personal computers can be connected as initiators.

[Means to solve the problem]

The circuit of the present invention includes an initiator circuit that operates as an initiator that sends instructions via the 5C3I bus, and a 5C3I bus.
The 5C3I bus control circuit includes at least one 5C3I bus control circuit including a target circuit that operates as a target in accordance with instructions received via the 3I bus.

Further, the circuit of the present invention has a configuration in which an SCSI bus is provided to connect to the initiator circuit, and an arbitrary number of target devices that operate as targets can be connected to this SCSI bus.

Further, the circuit of the present invention has a configuration in which SCSI buses corresponding to the number of target circuits are connected to the target circuits, and an arbitrary number of initiator devices that operate as initiators can be connected to this 5C3I bus. have

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a system configuration diagram of a first embodiment of the present invention. Referring to FIG. 1, a personal computer 1. Computer 2. The personal computer 3 is connected to the SCSI bus expansion circuit 5 via the SCSI bus 4, and the hard disk drive controller 6 as a target device is connected to the 5C3I bus expansion circuit 5 via the SCSI=5 bus 7. The SCSI bus 7 also includes a personal computer 8. as an initiator device. Computer 9. Computer 10. PC 1
1. Computer 12. A personal computer 13 is connected, and a hard disk drive 14 is connected to the hard disk drive controller 6.

Next, the operation of the personal computer 1 reading data from the hard disk drive 14 in the embodiment shown in FIG. 1 will be explained.

First, computer 1 is computer 2. 5 between computer 3
Wins the arbitration for the right to use the C3I bus 4 and secures the right to use the SCSI bus 4. Therefore, the PC 1 connects to the 5C3I bus expansion circuit 5 via the boat 1.
ID number O as the target device of 5csI bus 4
Send to.

The SCSI bus expansion circuit 5 uses the ID on the SC'SI bus 4.
The built-in target circuit recognizes that you have been selected as a target based on the number. Next, S
The CSI bus expansion circuit 5 operates as an initiator by the built-in initiator circuit 6, and
Arbitration is performed to win the right to use the CSI bus 7.

If it wins in this arbitration, the 5C3I bus expansion circuit 5 sends the ID number tone of the hard disk drive controller 6 to the SCSI bus 7. The hard disk drive controller has ID number 0 on the 5C3I bus 7.
The device recognizes that it has been selected as a target device and responds. In this way, the personal computer 1 and the hard disk drive controller 6 are connected to the SCSI bus 4SCSI.
Data transfer is possible via the bus expansion circuit and the 5C3I bus 7.

Next, the hard disk drive controller 6 is an SCS
A signal is issued to the I bus expansion circuit 5 to request a data read command. SC that received this signal
The SI bus expansion circuit 5 issues a signal to the personal computer 1 to request a data read command. In response to this signal, the personal computer 1 sends a data read command to the 5C3I bus expansion circuit 5. Having received this, the SCSI bus expansion circuit 5 sends the hard disk drive controller 6
Send a data read command to. Therefore, the hard disk drive controller 6 sends the data of the hard disk drive 14 to the SCSI bus expansion circuit 5, and the SCSI bus expansion circuit 5, which received this data, sends the data to the personal computer 1. After sending the data,
Next, the hard disk drive controller 6 is SCSI
A report of the command execution results is sent to the bus expansion circuit 5 as a status, and the SCSI bus expansion circuit 5, which has received the report, sends this status to the personal computer 1.

Next, the hard disk drive controller 6 sends a command completion message to the SCSI bus expansion circuit 5, and the SCSI bus expansion circuit that receives this message,
Send this message to PC 1. The personal computer 1 receives this message and finishes reading the data.

FIG. 2 is a system configuration diagram of a second embodiment of the present invention.

Referring to FIG. 2, personal computer 1. PC 2゜PC 3 connects to 5C3I bus expansion circuit 1 via 5C3I bus 4
9 is connected to the computer 15. Pankon 16. The personal computer 17 is connected to a SCSI bus expansion circuit 19 via a 5ISC bus 18. The hard disk drive controller 6 is connected to a SCSI bus expansion circuit 19 via a 5C3I bus 7. The SCSI bus 7 also includes a personal computer 8. Computer 9. Computer 10. PC 1
1. A personal computer 12 and a personal computer 13 are connected, and a hard disk drive 14 is connected to a hard disk drive controller 6.

In this second embodiment, the operation of the personal computer 1 to read data from the hard disk drive 14 will be explained.

First, computer 1 is computer 2. It wins arbitration with PC 3 and secures the right to use SCSI bus 4. On the other hand, if, for example, the personal computer 15 attempts to read data from the hard disk drive 14 between the personal computers 15 to 17, the personal computer 15 will read data from the hard disk drive 14.
The right to use the 3I bus 18 is secured. Therefore, computer 1
and the personal computer 15 each have a SCSI bus expansion circuit 19.
ID number 0 as the target of SCSI bus 4,S
Send it to the CSI bus 18. SCSI bus expansion circuit 19
learns the ID number on the SCSI bus 4, 5C3I bus 18 via the boat 1.2, and recognizes that it has been selected as a target by its built-in target circuit. In this embodiment, which of PC 1 and PC 15 is SC
Regarding whether to obtain the right to use the SI/<S expansion circuit 19,
Which 5C3I of SCSI bus 4 or SCSI bus 18
This depends on whether the 5C5I bus expansion circuit 19 recognizes the ID number on the bus first. Furthermore, if they are recognized at the same time, priority is given to boat 1. In this way, PC 1
Obtain the right to use the CSI bus expansion circuit 19. In other words, the personal computer 1 selects the 5C3I bus expansion circuit 19 as a target. Next, SCSI bus expansion circuit 1
9 operates as an initiator using a built-in initiator circuit, and performs arbitration to win the right to use the SCSI bus 7. If this arbitration wins, SCS I ) < large expansion circuit 19
The I bus of the hard disk drive controller 6 is connected to the I bus 7.
Send D number O. The hard disk drive controller 6 recognizes that it has been selected as a target based on the ID number on the SCSI bus 7, and responds.

Now the personal computer 1 and hard disk drive controller 6 are connected to the SCSI bus 4 and the SCSI bus expansion circuit 9.5.
Data transfer is possible via the C3I bus 7.

Next, the hard disk drive controller 6
A signal is issued to the SI bus expansion circuit 19 to request a data read command. This signal is sent to the personal computer 1 via the SCSI bus expansion circuit 19. Upon receiving this signal, the personal computer 1 sends a data read command to the hard disk drive controller 6 via the SCSI bus expansion circuit 19. Therefore, the hard disk drive controller 6 controls the hard disk drive 1.
4 is transferred to the personal computer 1 via one SCSI bus expansion circuit. After sending the data, the hard disk drive controller 6 then sends a report of the command execution results as a status via the 5C3I bus expansion circuit. Next, the hard disk controller 6 transfers a command completion message to the personal computer 1 via the SCSI bus expansion circuit 19. The personal computer 1 receives this message and the reading of the data is completed.

In this embodiment, the SCSI bus expansion circuit 19 has two built-in target circuits that operate as targets and controls two SCSI buses, so there is an advantage that more initiators can be connected.

〔Effect of the invention〕

As explained above, the present invention provides at least two 5C3
An S that includes at least one SCSI bus control circuit that includes an initiator circuit and a target circuit that control the I bus.
Connect to the CSI bus expansion circuit SCSI/<
By connecting a plurality of initiator devices to the SI bus control circuit, it is possible to significantly expand the number of initiator devices that can be connected in the SCSI bus system.

[Brief explanation of the drawing]

Figure 1 is a system configuration diagram of the first embodiment of the present invention;
This figure is a system configuration diagram of a second embodiment of the present invention, and FIG. 3 is a configuration diagram of a conventional SCSI bus system. 1-3...PC, 4...SCSI bus, 5...
・5csr bus, 8-12...PC, 14...
Hard disk drive, 15-17...PC,
18...SCSI bus, 19...SCSI bus expansion circuit, 20... Personal computer.

Claims (1)

[Scope of Claims] 1. At least one SCSI bus control circuit including an initiator circuit that operates as an initiator that sends instructions via the SCSI bus, and a target circuit that operates as a target in response to instructions received via the SCSI bus. A SCSI bus expansion circuit characterized by comprising: 2. The SCSI bus expansion circuit according to claim 1, further comprising a SCSI bus connected to the initiator circuit, and an arbitrary number of target devices operating as targets can be connected to the SCSI bus. 3. A SCSI bus corresponding to the number of target circuits is connected and arranged to the target circuit, and this SCSI bus is connected to the target circuit.
Claim 1 characterized in that an arbitrary number of initiator devices that operate as initiators can be connected to the bus.
SCSI bus expansion circuit described.