JPS6180348A - Bus switching device - Google Patents

Abstract

PURPOSE:To simplify bus switching operation and to prevent a bus switching device from malfunction by monitoring the state of computers and controlling bus switching so that an I/O device is not connected to the computer stopped at its operation. CONSTITUTION:State monitoring circuits 22, 24 for monitoring the state monitoring signals 21, 23 of the computers 5, 7 are formed in a bus switching device 1. The computers 5, 7 and an I/O device 2 are connected to a bus switching control device 9. The circuit 9 controls the bus switching on the basis of the outputs of the circuits 22, 24 so that the device 2 is not connected to the computer stopped at its operation.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a system in which two or more computers and one or more input/output devices are connected by a bus. This invention relates to a bus switching device that switches connections.

[Conventional technology]

In a computer system composed of a plurality of computers and a plurality of input/output devices, a bus switching device is used to organically connect each device and operate the computer system efficiently.

This type of bus switching device switches the bus between multiple computers and shared input/output devices for the purpose of improving processing power and reliability, or it is used from an economic standpoint and installation space. From the standpoint of saving money, some computers switch buses in order to share expensive and infrequently used input/output devices with each computer.

This type of bus switching device is often required when an input/output device that has been operating in one computer system is to be shared with a newly installed computer system in another system. In existing computer systems, even if a bus switching device is connected, the software must not be changed, and the basic requirement is to switch the bus switching device manually. The structure is as follows.

FIG. 3 shows a configuration diagram of a computer system using a conventional bus switching device. In this Figure 3, (1)
is a bus switching device, and (2) is a shared input/output device.

(S) is computer A, (7) is computer B, (,?) is bus C to input/output device -), (7) is computer A (&)
Bus A from (za) is computer B Bus B from (?)
, (4') is a bus changeover switch which is a manual changeover means, and (q) is a bus changeover control circuit, that is, a control means.

In such a configuration, the bus switching device (1) manually switches the bus C(3) of the shared input/output device (, 2) to the bus A( of the computer A(j)) using the switch means (4'). 6) or bus B (f
A bus switching control circuit (9) is used to select whether to connect to f).

[Problem that the invention seeks to solve]

As mentioned above, conventional bus switching devices only have a manual switching function, e.g.

When trying to operate your own computer system,
Assume that the switch of the bus switching device is set to the computer system side of another system.

The input/output device is connected to the computer system of the other system by the bus switching device, even though the computer system of the other system is not powered on and therefore is not in operation or used. There was a problem in that it required manual switching. For example, if the own computer system is in operation,
If the computer system of another system is not in operation, if the switch of the bus switching device is operated incorrectly, the connection between the connected input/output device and the computer system of the own system will be severed, causing a failure. There was also the problem that there was a risk of overshooting.

This invention was made to solve the problems in the conventional bus switching device described above.

The object of the present invention is to provide a bus switching device that includes a monitoring means for monitoring the status of each computer system and prevents the switching means of the bus switching device from being connected to a computer system that is not in operation. .

[Means for solving problems]

The bus switching device according to the present invention is constructed by providing means for monitoring the state of a computer to be connected to a shared input/output device.

[For production]

In the computer system using the bus switching device of the present invention, the state of the target computer is monitored by the monitoring means provided in the bus switching device, and the state representing the monitoring result and the computer keeper output device are connected to each other. When a predetermined logical relationship is established between the manual switching means (4') and the operating state of the manual switching means (4') for switching the connection, the intended switching operation is carried out.

〔Example〕

Below, a bus switching device that is an embodiment of this invention will be described.

This will be explained with reference to FIG. 1 and FIG.

First, referring to FIG. 1, this is a block diagram illustrating the configuration of a computer system using a bus switching device according to the present invention. Note that in FIG. 1, the same reference numerals as in FIG. 3 indicate the same or corresponding parts. In this Figure 1, (col) is computer A (
, t) state monitoring signal A.

(2) is a status monitoring circuit (monitoring means) A that monitors the status monitoring signal A (1), (2, y) is the status monitoring signal B of the computer (7), (1I) is the status monitoring circuit Signal B(λ
3) is a state monitoring circuit (monitoring means) B that monitors.

Next, FIG. 1 is a circuit diagram illustrating the configuration of the bus switching device (1) in FIG. 1 in detail. In FIG. 2, each bus is shown with one input signal line and one output signal line, in order to avoid the complexity of one circuit diagram. In FIG. 2 as well, the same reference numerals as in FIG. 1 or 3 indicate the same or corresponding parts.

The status monitoring signal (co/) and (23) are each from computer A.
(S) and B (?) are powered on and are operating normally. For example, the clock signal A on bus A (6) and the clock signal on bus B (ff
) may be the clock signal B on the top.

The status monitoring circuits (,22) and (coll) detect the clock signal A (co/) and the clock signal B (x3), respectively, and indicate that the computer A (,t) is operating effectively.
A circuit that outputs a signal to the box indicating that the OK signal, calculator, and B(7) are operating effectively, and the time constant is set to output a pulse longer than the clock cycle, for example, using a clock signal as a trigger. Consists of retriggerable one-shots. Therefore, when one shot A (j, 2) receives clock signal A (: maintain.

One shot B (, 24A) operates in the same way and the BOX
Outputs a signal to. (31) is a flip-flop FFA that has set and reset input terminals and controls the connection between bus A (A) and bus C (3), and its output signal AON @ is a logic ” to instruct the connection.

The logic ``'θ'' indicates separation. Similarly, (3) is a flip-flop FFB that controls the connection between bus B (g) and bus C (3), and outputs a B ON signal. In addition.

For both FFA (, ?/) and FFB (, ?, 2), when a set signal and a reset signal are input at the same time, the reset signal takes priority. (,?,?), (,?da),
(, y, t), (, yA) are bus drivers, and the AON signal turns on driver f (33) and (3q), and the bus A (A) and bus C (3) are turned on. Also, the BON signal turns on drivers (3) and (3t), and buses B (t) and (3) are connected.

(3) is an AND that controls the set of FFA (,?/)
(3g) is an AND gate that controls the set of FFB (32).

(39) is an OR that suppresses the reset of FFA (,?/)
(lIo) is an OR gate that controls the reset of FF'B (, ?).

The switch (4') connects the input/output device (:2) between the input/output device (4(a)) and the input/output device (2) on the computer B (7) side. This is a momentary switch consisting of a contact section (Ilb) that outputs a connection signal.When pressed, the corresponding contact section opens and generates a predetermined connection instruction signal.

(lIl) is an AND gate that gates the connection instruction signal from the contact part (4Ia), and when the AOK signal is logic "L", the connection instruction signal is
, and further OR game) (tIO') to FFB
(,?ko) is reset.

(4I) is an AND gate that gates the connection instruction signal from the contact part (4th), and the BOK signal is logic "1".
At this time, the connection instruction signal of the switch passes through this AND gate (Kuco) and further passes through the OR gate (39) to reset the FFA (3/).

Next, the operation of the bus switching device according to the present invention configured as described above will be explained.

(L) First, when computers A (r) and B (7) are powered off, clock signals A (2/) and B (3) do not exist, and the output AOK of one shot A (22)
The output BOX signal of the signal and one-shot B (a4) are both logic 1θ". The inverted signal of the AOK signal passes through the OR gate (39), resets the FFA (,?/), and the inverted BOX signal. The signal is an OR gate (41o)
The FFB(,?,2) is reset through A.
Both the ON signal and the BON signal are in the logic "θ" state. Therefore, bus drivers (3J), (3
4t), (:ts).

(36) are both off, and bus c (3) is bus A.
(A) It is in a disconnected state where it is not connected to either VC or bus B.

Here, when the computer A (j) is powered on, the clock signal A (:l/) is input to the one-shot Anko), the AOK signal becomes logic "l", and the FFA (,?
At the same time that the reset state of /) is released, FFA (,?/) is set through the AND gate (3).

When FFA (31) is set, the AON signal becomes logic
'l' is output and the bus driver (,?,?)
,(,? is turned on, bus A (6) and bus C (3
) is logically connected.

In this way, computer A (j-) is powered on.
When the input/output device (2) is automatically connected to the AO
The inverted signal of the N signal is input to the AND game) (3g), and the computer B (7) is then powered on and becomes BC)K.
Even if the signal is output, the logic condition of the AND gate (3g) is not satisfied, so FFB (, y2) is not set, and the bus switching device connects bus A (6) and node C (3). maintain the condition.

In addition, when the power of computer B (7) is not turned on, the BOX signal is logic "O", and even if the contact part (lIb) is operated at this time, the logic condition of the AND gate (4') is not changed. bus A (6) and bus C (3
) stay connected.

Next, computer B (wa) is powered on with bus A (6) and bus C (3) connected, and the input/output device (:
If you want to connect 2) to computer B (7), that is, if you want to connect node C (3) to bus B (g), just operate the contact part (llb). The signal of the contact part (llb) is passed through the AOD gate (lb) because the BOX signal has become logic "l" when the computer B (7) was powered on.

Reset FFA (,?/). From this k, AON
The signal becomes logic “o” and connects bus A (AI and bus C (3
) is separated and the inverted signal of the AON signal is input.The BOX signal is input to FFB through (3g').
(,?ko) is input to the set terminal of FFB(,?,2
) is set and the BON signal becomes logic "L". Then, when the BON signal becomes logic "L", the bus drivers (33) and (36) are turned on, and the bus B
(ff) and bus C (,?) are brought into a connected state.

By operating the contact part (+b) in the above sequence, bus C (,?) is changed from bus A (6) to bus B (f).
The connection is switched to

Similarly, switching the connection from bus B (g) to bus A (6) is performed by operating the contact portion (41a).

When computers A (, t) and B (7) are both powered on and the AOK and BOX signals are logic "1", the AND gate (41t), (guco) turns on the switch (4'3). Since it is possible to pass the connection instruction signal from the main unit, manual switching can be performed arbitrarily as needed.

Furthermore, in the above state, bus C (3'J is bus A (A
), when the computer A (51) is powered off, the clock signal A(,2/) disappears,
AOK No. a becomes logic “o” and its inverted signal becomes O.
FFA (3/) is reset through (,?9).

When the AON signal becomes logic ``0'', the bus C (3
) and bus A (6) are separated. At the same time, the A
The inverted signal of the ON signal is input to the AND gate (3g), the logic condition with BOX 4g is satisfied, and FF'B (J
t2) is set, and the BON signal is made logic "1".

Bus C(3) is connected to bus B(Z).

In other words, this bus switching device is controlled so that it is not connected to a computer that is not operating.

For example, when computer A (5) is powered off, the input/output device (2) is automatically switched to and connected to computer B (7).

In addition, in the above embodiment, the computer status monitoring signal and (1) I have shown what the clock signal is used for.

It may also be a signal related to the power supply for the computer's electronic circuit.

Alternatively, it may be any signal on the bus.

Further, in the above embodiment, a switching circuit using an electronic circuit is shown as the bus switching circuit, but a mechanical switching circuit using a relay or the like may be used.

〔Effect of the invention〕

As explained above, according to the present invention, a monitoring means for monitoring the status of a computer is provided in the bus switching device, and a signal from the monitoring means prevents input/output devices from being connected to a computer that is not operating. Since the configuration is configured to control bus switching, when the system starts up, the input/output device is connected to the computer that started up first, and the computer that started up later maintains the previous connection state, and , the changeover switch.

When one or more systems of dividers are running, switching can only be performed between the dividers. Furthermore, when the connected computer goes down.

It is also possible to automatically switch to the normal computer side.

These functions are effective in simplifying bus selection switch operation and preventing erroneous operation.

Furthermore, when an input/output device that has been incorporated and operated in an existing computer system is to be shared with a newly introduced computer, the software of the target computer can be changed without making any changes to the software of the existing computer system. This has the effect that automatic switching control is performed depending on the state.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the configuration of a computer system using a bus switching device according to the present invention. FIG. 2 is a circuit diagram illustrating the configuration of the bus switching device U in the IC, and FIG. 3 is a block diagram illustrating the configuration of a computer system using the conventional bus switching device. 4 1...Bus switching device, code/input/output device, 3゜6,za...
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Claims (3)

[Claims] (1) A bus switching device that switches connections between computers and input/output devices in a system in which two or more computers and one or more input/output devices are connected by a bus, the bus switching device The switching device includes a switching device that manually switches the computers connected to the input/output device, a monitoring device that monitors the status of each computer, and a switching device that receives an output signal from the monitoring device and switches the computers that are not operating. 1. A bus switching device comprising: control means for controlling the bus so that the bus is not connected to the other side of the bus. (2) The control means controls the switching means to switch the input/output device on the operating computer side when the connected computer stops operating due to system down. A bus switching device according to claim 1. (3) The control means controls the switching means so that when the system starts up, the input/output device is connected to the computer that started up first. Bus switching device.