JPH0437459B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a balanced/unbalanced conversion device for a SCSI bus that interconnects a balanced SCSI device and an unbalanced SCSI device.

(Prior technology) SCSI (small computer system interface)
is a parallel bus interface for small computers, and ANSIX3T9.2 is currently promoting standardization.

There are two types of SCSI devices:

Balanced SCSI device The potentials on the two conductors are equal with respect to ground,
It uses a transmission line that is symmetrical about the ground point. The maximum extension distance is 25m, which is long, but there are two signal lines in a set, which increases equipment costs.

Unbalanced SCSI device A device that uses a transmission line in which the potentials on the two conductors are not equal with respect to the ground. If there is a grounding wire, only one signal wire is required, which reduces equipment costs, but
The maximum extension distance is shortened to 6m.

(Problem to be solved by the invention) However, as far as the applicant currently knows,
There is no device that interconnects balanced and unbalanced SCSI devices.

Considering the case where the system becomes widespread, if the two types coexist and cannot be interconnected, an unfavorable situation will occur in terms of system construction.

The present invention solves these problems,
The object of the present invention is to provide a balanced/unbalanced conversion device for a SCSI bus that interconnects a balanced SCSI device and an unbalanced SCSI device.

(Means for Solving the Problems) The first invention to achieve such an object is a balanced transceiver that exchanges data with devices connected to a balanced SCSI bus, and an unbalanced SCSI bus. An unbalanced transceiver that exchanges data with connected devices, a SCSI protocol controller that is attached one-to-one with each of these balanced and unbalanced transceivers, and a It consists of a bus that interconnects type and unbalanced type transceivers.

To explain the details of the SCSI protocol controller,
If the transmitter/receiver is a balanced type, a unique identification name corresponding to a device on an unbalanced SCSI bus is given; if the transmitter/receiver is an unbalanced type, a unique identification name corresponding to a device on a balanced SCSI bus is given. An identification name setting section that stores an identification name unique to the own station, and an identification name setting section that stores an identification name unique to the own station, and when a request for sending or receiving data from another station sends an identification name that is the same as the identification name of the own station, the identification name of the other station. It has a destination storage unit that stores the name of the destination, and when the identification name of the destination storage unit is set, it activates the SCSI protocol controller with the corresponding identification name and communicates between them. It is.

A second invention that achieves these objects includes a balanced transceiver that transmits and receives data to and from devices connected to a balanced SCSI bus, and a balanced transmitter and receiver that transmits and receives data to and from devices that are connected to an unbalanced SCSI bus. An unbalanced transceiver, a SCSI protocol controller that is attached one-to-one to each of these balanced and unbalanced transceivers, and a DMA bus that interconnects these SCSI protocol controllers and is used for DMA transfer. ,
It consists of a bus switching unit that monitors the transmission and reception status of these SCSI protocol controllers and establishes a data path for communication.

To explain the details of the bus switching section, in the SCSI data transfer phase, the bus is used to connect the SCSI protocol controllers that manage devices.
It selects the DMA bus and selects the processor bus during SCSI message, command, and status phases.

(effect) Each component of the first invention operates as follows.

First, devices connected to a balanced SCSI bus have a unique identification name, and devices connected to an unbalanced SCSI bus also have a unique identification name.

The balanced and unbalanced transceivers are connected to the balanced and unbalanced SCSI buses, respectively, so that they can communicate with each device.

When a SCSI protocol controller is connected one-to-one with a balanced transceiver, it has an identification name for associating it with a device connected to an unbalanced SCSI bus. In addition, when a SCSI protocol controller is connected one-to-one with an unbalanced transmitter/receiver, the SCSI protocol controller is a balanced type.
It has an identification name to associate with devices connected to the SCSI bus.

When a communication request is made from a device on the balanced SCSI bus side to a device on the unbalanced SCSI bus side, the SCSI protocol controller corresponding to the identification name of the device on the unbalanced SCSI bus side that made the request via the SCSI bus Specify the contents of this station's destination storage (balanced SCSI
respond based on the identification name of the device (device on the bus side)
Specifies the SCSI protocol controller. In this way, connect between SCSI protocol controllers
The use of the DMA bus and processor bus is permitted to allow devices connected to the SCSI bus to communicate directly.

Each component of the second invention operates as follows.
The same components as in the first invention have the same effect. The DMA bus is used exclusively for data transfer, which helps reduce communication time. The processor bus is used for data transfer when complex processing such as state phase is required. The bus switching unit is connected to the DMA bus and processor bus.
Switch combinations between SCSI protocol controllers.

(Example) The present invention will be explained below using the drawings.

FIG. 1 is a block diagram schematically explaining the concept of an embodiment of the present invention. As shown in the figure, computers and disks each having a unique identification name (ID) are connected to the balanced SCSI bus. For example, these are #1, #2, . . . , #k, and there are k in total. Computers, tapes, etc. each having a unique identification name are also connected to the unbalanced SCSI bus. For example, let these be #k+1, . . . , #k+l, and there are l in total. The SCSI bus balanced/unbalanced converter is a balanced type.
It is interposed between the SCSI bus and the unbalanced SCSI bus.

FIG. 2 is a block diagram conceptually showing the structure of a SCSI bus balanced/unbalanced conversion device.

A balanced SCSI bus has an identification name that corresponds to each device connected to the unbalanced SCSI bus.
SCSI protocol controller (SPC)
A balanced transmitter/receiver (D/R: SCSI driver receiver) is installed in series. According to the example in Figure 1, the identification name of the SCSI protocol controller is #k+
1,..., #k+l. Note that the SCSI protocol controller is available as MB87030 supplied by Fujitsu Ltd., for example.

An unbalanced SCSI bus has an identification name that corresponds to each device connected to the balanced SCSI bus.
A SCSI protocol controller (SPC) and an unbalanced transmitter/receiver (D/R) are installed in series. According to the example in Figure 1, the identification name of the SCSI protocol controller is #1,
#2,..., #k.

A DMA bus connects all SCSI protocol controllers #1,..., #k+l. The processor bus also connects all the SCSI protocol controllers #1, . . . , #k+l. SCSI
These connections between the protocol controller and the transceiver
The DMA bus and processor bus are connected by a multiplexed bus.

A microprocessor (MPU) and memory (RAM and ROM) are also connected to the processor bus. The MPU monitors the transmission/reception status of the SCSI protocol controllers and uses the bus to connect two SCSI protocol controllers to manage devices to communicate with the DMA in the SCSI data transfer phase.
It operates as a bus switching unit that selects a bus and selects the relevant processor bus during SCSI message, command, and status phases.

FIG. 3 is a configuration block diagram of a transmitting/receiving circuit of an unbalanced SCSI bus. For transmission, an element such as LS38 is used for each bit of the output parallel data bus SDBO. For reception, an element such as LS240 is used for each bit of the input parallel data bus SDBI.

FIG. 4 is a block diagram of the configuration of a transmitter/receiver circuit for a balanced SCSI bus. Parallel data bus for output
A transmitting element is provided for each bit of SDBO, a receiving element is provided for each bit of input parallel data bus SDBI, and an output enable parallel data bus SDBE is supplied to these transmitting elements.

FIG. 5 is a block diagram of the configuration of the SCSI protocol controller. In the figure, reference numeral 11 denotes a transfer control unit that supplies information necessary to control bus transfer, and controls, for example, request signals and acknowledge signals. Reference numeral 12 denotes a phase control unit that supplies information necessary to control the phases of the bus, and controls, for example, message signals, command signals, and status signals. Reference numeral 13 denotes a bus exclusive right contention management unit that supplies information necessary for bus management, and controls select signals and busy signals to control contention on the SCSI bus.

14 is a data transfer counter that manages the number of data transfers executed by the transfer control unit 11. 15
is a data buffer that adjusts the input/output speed when transferring data from a transceiver to another transceiver or data buffer. 16 is an ID setting unit that stores the identification name of the SCSI protocol controller, and this identification name may be supplied from the MPU at startup, for example, or
Set this in advance using a DIP switch, etc. 1
7 is a device connected via a bus, and
This is a destination ID storage unit that stores the identification name of the device that selected the SCSI protocol controller. 18 is
This is an interrupt signal generation unit that temporarily stops the operation of the MPU and gives priority to interrupt processing, and operates when an identification name is written in the destination ID storage unit 17.

Further, when the identification name is written in the destination ID storage unit 17, the processor learns the identification name through the processor bus and activates the SCSI protocol controller having the same identification name as the device that made the call.

The operation of the device configured in this manner will be described next. Here, in Figure 1, from device #k on the balanced SCSI bus to device #k+ on the unbalanced SCSI bus.
Let's take as an example the case of communicating with device l. As shown in Figure 2, from device #k on the balanced SCSI bus
A request flows to the SCSI bus, and the identification name is #k+l.
The SCSI protocol controller receives this. Then, the identification name #k of the caller is stored in the destination ID storage unit 17.
is set. Next, the microprocessor learns from the interrupt from the SCSI protocol controller with identification name #k+l that the identification name of the source device is #k, and puts the SCSI protocol controller with identification name #k into the sending state. Set.

In this way, a communication path is established from device #k to transceiver #k+l to transceiver #k to device #k+l.

The MPU operates as a bus switching unit, and when exchanging information without performing any processing on the data, such as in DMA transfer, the DMA bus achieves high speed. Furthermore, when appropriate processing is required depending on the data, such as with stator signals, a processor bus is used to enable a microprocessor to process data exchange.

(Effects of the Invention) As explained above, the present invention has the following effects.

When the SCSI bus balanced/unbalanced conversion device is configured as in the first and second inventions, a balanced type
Communication between devices connected to the SCSI bus and devices connected to the unbalanced SCSI bus is possible.

If a plurality of buses are provided and used by switching according to information as in the second invention, the data transfer time by the SCSI bus balanced/unbalanced converter can be shortened.

As in the example, when a communication path is established using the communication function of the device connected to the SCSI bus,
The load on the MPU is extremely light, and the load on the MPU is extremely light.
Transparent when recognizing the SCSI bus balanced/unbalanced conversion device, that is, communication between balanced (or unbalanced) SCSI devices and communication between balanced and unbalanced SCSI devices It is easy to handle because it can be handled in the same way regardless of the case.

[Brief explanation of drawings]

FIG. 1 is a configuration block diagram schematically explaining the concept of an embodiment of the present invention, FIG. 2 is a configuration block diagram conceptually illustrating the configuration of a SCSI bus balanced/unbalanced conversion device, and FIG. The figure shows the configuration block diagram of the transmitter/receiver circuit of an unbalanced SCSI bus, and Figure 4 shows the configuration of the unbalanced SCSI bus transmitter/receiver circuit.
Configuration block diagram of SCSI bus transmitting/receiving circuit, Part 5
The figure is a block diagram of a SCSI protocol controller. D/R...transmitter/receiver, SPC...SCSI protocol controller.

Claims (1)

[Claims] 1. A balanced transceiver that exchanges data with a device connected to a balanced SCSI bus, and an unbalanced transceiver that exchanges data with a device connected to an unbalanced SCSI bus. , is attached one-to-one with each of these balanced and unbalanced transceivers, and if the transceiver is a balanced type, a unique identification name corresponding to the device on the unbalanced SCSI bus is given, and the transceiver is If the device is an unbalanced type, a unique identification name corresponding to the device on the balanced SCSI bus is assigned, and an identification name setting section that stores the unique identification name of the own station and requests for sending and receiving data from other stations are assigned. The balanced type and a bus for interconnecting unbalanced transceivers, and when an identification name is set in the destination storage section of the SCSI protocol controller, the SCSI protocol controller with the corresponding identification name is connected via the bus; A SCSI bus balanced/unbalanced conversion device characterized by activating a SCSI bus and communicating between them. 2 Balanced transceivers that exchange data with devices connected to a balanced SCSI bus; unbalanced transceivers that exchange data with devices connected to an unbalanced SCSI bus; It is attached one-to-one with each balanced transceiver, and if the transceiver is a balanced type, a unique identification name corresponding to an unbalanced SCSI bus device is given; A unique identification name corresponding to the equipment on the balanced SCSI bus is assigned, and an identification name setting section stores this unique identification name for the own station, so that requests for sending and receiving data from other stations are the same as the identification name of the own station. A SCSI protocol controller has a destination storage unit that stores the identification name of the destination when the identification name of the destination is sent, and the balanced type and unbalanced type transceiver are mutually connected via these SCSI protocol controllers. A DMA bus that interconnects these SCSI protocol controllers and is used for DMA transfer. A SCSI protocol controller that monitors the transmission and reception status of these SCSI protocol controllers and manages the devices that communicate with them. In the SCSI data transfer phase, select the DMA bus to connect between
Phases such as SCSI messages, commands, and statuses are comprised of a bus switching unit that selects the relevant processor bus, and when an identification name is set in the destination storage unit of the SCSI protocol controller, correspondence is provided via the processor bus. A balanced/unbalanced conversion device for a SCSI bus, characterized in that the device activates a SCSI protocol controller having an identification name to communicate between these controllers.