JPS6213733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a magnetic tape system that allows data to be read/written in high speed mode and low speed mode.

Conventional magnetic tape devices include a supply reel, take-up reel, capstan, magnetic head, vacuum
It consists of a column, magnetic tape, etc.
This type of magnetic tape device has an interblock
It is structured so that it can be started/stopped between gears, and has excellent characteristics, but it has the disadvantage of being expensive as it requires high-performance capstans, vacuum columns, etc. have.

In order to eliminate the above-mentioned drawbacks, it has already been proposed to omit the capstan, vacuum column, etc., and directly control the running speed of the magnetic tape by the rotation of the take-up reel and the supply reel. Such magnetic tape systems have two modes: a high-speed mode (Streaming Mode) in which data blocks are read/written continuously at high speed, and a low-speed mode (Start/Stop) in which data blocks are read/written intermittently at low speed. Mode). The high-speed mode is a high-speed drive method for loading/dumping data, and is a high-speed drive to increase the data transfer speed. In the high speed mode, the time and distance from driving to reaching high speed or from high speed to stopping are set to be sufficiently large. In low speed mode, it is designed to start/stop with conventional 0.6" interblocks for journaling purposes, etc.

Figure 1 explains the high-speed mode and low-speed mode. In the figure, MT is a magnetic tape,
D _i-1 to D _i+4 indicate data blocks, respectively. FIG. 1A explains the operation when, for example, reading reaches data block Di in high-speed mode and then stopping, and then reading from data block D _i+1 again in high-speed mode.
When reading of the data block Di is completed, the drive signal is turned off, and the magnetic tape MT decelerates and stops. Magnetic tape after the drive signal is turned off
The distance S until the MT stops is measured by a distance measuring means. Next, when a read instruction is sent again, the magnetic tape MT is moved in the opposite direction along path a, and at the point where it has moved by a distance equal to distance _S1 , the drive signal is turned off, and the magnetic tape MT route b
The vehicle will decelerate and stop accordingly. The travel distance _S2 when traveling along route b is also measured by the travel distance measuring means. Next, the magnetic tape MT is moved in the forward direction along the path C, and reading of the data block is started at the point where it has moved by a distance _S2 .
Figure 1B shows, for example, the data block in low speed mode.
This is an explanation of the operation when reading up to D i and stopping, and then reading from data block D _i+1 again in low speed mode. Low speed mode 2
As in the conventional magnetic tape system, when reading data block D _i+1 , reading can be started immediately after turning on the drive signal.

Now, consider the case where after reading up to data block Di in high speed mode, reading is performed again from data block D _i+1 in low speed mode. In this case, the magnetic tape MT is connected to the data blocks Di and D _i
It is necessary to return to the inter block gap IBGi between ₊₁ and start reading. Also, considering the case where data is read to data block Di in low speed mode, and then read from data block D _i+1 in high speed mode, the magnetic tape MT is advanced to inter block gap IBG _{i+2, and then read from data block D i+1} in high speed mode. Afterwards, it is necessary to perform a reposition operation and then read data block D _i+1 . However, it is assumed that a reposition operation is always required when reading/writing in high-speed mode.

It may be possible to execute the space operation required when switching the speed mode as described above when executing a read command or a write command, but if this is done, a selector channel etc. will be used as the channel. In this case, the channel is exclusive to the magnetic tape controller that issued the command even during the space operation, resulting in a drawback that the efficiency of the entire input/output system is significantly reduced. In addition, when executing read/write commands in high-speed mode, read/write starts after repositioning the magnetic tape, and when executing read/write commands in low-speed mode, the magnetic tape is run and read/write is started immediately. If writing is to be started, performing the space operation necessary for speed mode switching when executing a read/write command has the disadvantage of unnecessarily complicating control.

The present invention eliminates the above-mentioned drawbacks in a magnetic tape system that performs read/write operations at two tape running speeds without reducing overall system efficiency or complicating control. , magnetic tape that can perform the processing required when switching speed modes.
The purpose is to provide a system. Therefore, the magnetic tape system of the present invention
It is equipped with a magnetic tape device, a magnetic tape control device for controlling the magnetic tape device, a channel, and a status control circuit, and the status control circuit has a high speed mode or a low speed mode depending on the magnetic tape control device. Status information such as speed designation information indicating forward or reverse direction, read/write designation information indicating read or write is stored, and the status information of the above-mentioned status control circuit controls the magnetic tape. In a magnetic tape system in which the speed and direction as well as the write and playback circuits of the magnetic tape device are controlled, the channel is capable of receiving a speed mode switching command such as a fast mode switching command or a slow mode switching command. The magnetic tape control device is configured to send a response signal to the channel, and upon receiving the speed mode switching command from the channel, the magnetic tape control device immediately sends back a signal to the channel to release the monopoly of the channel by the magnetic tape device. and a positioning control that reads out the status information of the status control circuit when receiving the speed mode switching command and performs control to move the magnetic tape to a position determined by the nature of the speed mode switching command and the content of the status information. The invention is characterized by comprising a part. Hereinafter, the present invention will be explained with reference to the drawings.

FIG. 2 is a block diagram of one embodiment of the present invention. In Fig. 2, 1 is a supply reel, 2 is a take-up reel, 3 is a reel motor, 4 is a magnetic head,
5 is a rotating body, 6 is a tachometer, 7 is a reel motor drive control circuit, 8 is a reproducing circuit, 9 is a writing circuit, 1
0 indicates a tacho pulse counter, 11 a status control circuit, and 12 a magnetic tape control device.

Assume that reading is now being performed at high speed and in the forward direction. In this state, the high speed mode, forward direction, and read status are set in the status control circuit 11, and the drive signal is set to logic "1".
It is said that Assuming that the data block Di is the last data block as shown in FIG. 1, the magnetic tape controller 12 turns off the drive signal when it detects the interblock gap IBGi. When the drive signal is turned off, the magnetic tape 7
decelerates and stops, and at the same time the tacho pulse counter 10 starts counting up the tacho pulses. Note that after the drive signal is turned off, the connection between the magnetic tape control device 12 and the magnetic tape device is disconnected. After the magnetic tape MT has completely stopped, a logic "1" data ready signal is sent to the magnetic tape controller 12, indicating that the count value of the tacho pulse counter 10 indicates the correct distance traveled at the time of stop. do. Next, when starting reading from data block D _i+1 in the high speed mode and in the forward direction, the magnetic tape controller 12 performs repositioning as shown in FIG. 1B while changing the contents of the status control circuit 11. , data block D
Start reading from _i+1 .

When reading is performed at low speed and in the forward direction, the status control circuit 11 has a low speed mode,
Forward and read status is set,
The drive signal is set to logic "1". Assuming that the data block Di is the last data block as shown in FIG. 1B, the magnetic tape controller 12 turns off the drive signal when it detects the interblock gap IBGi. In low speed mode, the magnetic tape MT stops at the interblock gap. When reading in the low speed mode and forward direction again, the drive signal is turned on,
The magnetic tape controller 12 immediately starts reading.

In the present invention, when reading from a high speed mode to a low speed mode, for example, the central processing unit (not shown) is connected to the magnetic tape controller 1 via a channel.
2, first a low speed mode switching command is sent, and then a read command is sent. Note that, in principle, the central processing unit sends out a speed mode switching command only when it is necessary to switch the speed mode. When the magnetic tape control device 12 receives the low-speed mode switching command,
Immediately return the channel end to the channel.
When the channel end is sent out, the interface between the channel and magnetic tape controller 12 is disconnected. After receiving the low-speed mode switching command, the magnetic tape control device 12 switches the status control circuit 1 to the low-speed mode switching command.
Sense the status within 1. Now, assuming that the status in the status control circuit 11 is high speed mode, forward direction, and read, the magnetic tape control device 12 changes the status to low speed mode, reverse direction, and read, and the magnetic tape MT is controlled by the tacho pulse counter. 10 in the reverse direction and then stopped, and then the reverse direction status in the status control circuit 11 is changed to the forward direction, and the tacho pulse counter 10 is set to all "0". When a low speed mode switching command is received,
When the status in the status control circuit 11 is high speed mode, reverse direction, read, the magnetic tape is moved in the forward direction at a low speed by the content of the tacho pulse counter 10, and then the forward direction status changes to the reverse direction. Modified tacho pulse counter 1
The contents of 0 are cleared.

When receiving the high speed mode switching command, the magnetic tape controller 12 executes the following space operation. When the status in the status control circuit 11 is low speed mode, forward direction, read,
With these statuses unchanged, the magnetic tape MT is moved forward by a predetermined distance with the tacho pulse counter 10 in the count enable state, and then the low speed mode status in the status control circuit 11 is changed to the high speed mode status. change. When the high-speed mode switching command is received, the status in the status control circuit 11 is
If the mode is low speed mode, reverse direction, or lead, keep these statuses as they are and use the tacho pulse.
The magnetic tape MT is moved in the opposite direction by a predetermined distance with the counter 10 in a counting enable state, and then the low speed mode status in the status control circuit 11 is changed to the high speed mode. Incidentally, when the speed mode switching command is received, if the write status is set in the status control circuit 11, the write status is changed to the read status and the space operation described above is performed.

FIG. 3 shows one embodiment of the main parts of a magnetic tape control device. In FIG. 3, 13 is a command receiving section, 14 is a response signal sending section, 15 is a command decoding section, 16 is a positioning control section, 17 and 18
indicate the input and output interfaces, respectively.
The command receiving unit 13 receives the command sent from the channel and sends it to the command decoding unit 15.
give it to The command decoder 15 determines what type of command the passed command is, and sets the signal on the corresponding output line to logic "1". When the response signal sending unit 14 is notified that the command sent from the channel is a speed mode switching command, the response signal sending unit 14 sends the channel end back to the channel. Further, upon receiving the speed mode switching command, the positioning control section 16 is activated. The positioning control unit 16 performs positioning of the magnetic tape based on receipt of the speed mode switching command. The positioning control section 16 can read/write the status control circuit 11 via the input/output interface 17. Although not shown, the status control circuit 11 is composed of a flip-flop for speed designation, a flip-flop for direction designation, a flip-flop for read/write designation, and a flip-flop for count enable. The output of the flop is sent to the corresponding device. The positioning control section 16 also controls drive signals. The positioning control unit 16 can read the contents and tacho pulses of the tacho pulse counter 10 via the input/output interface 18, and
A clear signal can be sent.

FIG. 4 is a flowchart illustrating processing when a speed mode switching command is received. Note that the details of the process when the speed mode switching command is received have already been explained, so a brief explanation will be given here.

When receiving the speed mode switching command, it reports the channel end to the channel.

Read the contents of the status control circuit.

Check whether the speed mode switching command specifies switching from high speed to low speed. Processing is performed when the speed is low to high, and processing is performed when the speed is low.

Enables the tachopulse counter to count.

Drive the magnetic tape a fixed distance.

Change the contents of the status control circuit.

Change the contents of the status control circuit.

The magnetic tape is driven in accordance with the count value of the tacho pulse counter.

Change the contents of the status control circuit.

As is clear from the above description, according to the present invention, it is possible to prevent a channel from being monopolized by one magnetic tape control device for a long time, and to control the execution of read/write commands or commands. You can obtain effects such as things that can be done easily.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the high-speed mode and low-speed mode of the magnetic tape system that is the basis of the present invention, FIG. 2 is a block diagram of one embodiment of the present invention, and FIG. 3 is a diagram illustrating the main components of the magnetic tape control device. FIG. 4 is a flowchart illustrating processing when a speed mode switching command is received. 1... Supply reel, 2... Take-up reel, 3...
Reel motor, 4...Magnetic head, 5...Rotating body, 6...Tachometer, 7...Reel motor drive control circuit, 8...Reproduction circuit, 9...Writing circuit, 1
0...Tacho pulse counter, 11...Status control circuit, 12...Magnetic tape control device.

Claims (1)

[Scope of Claims] 1. A magnetic tape device, a magnetic tape control device that controls the magnetic tape device, a channel, and a status control circuit, the status control circuit including a magnetic tape control device that controls the magnetic tape device. Status information such as speed designation information indicating high speed mode or low speed mode, direction designation information indicating forward or reverse direction, and read/write designation information indicating read or write is stored, and status information of the status control circuit is stored. In a magnetic tape system in which information controls the speed and direction of the magnetic tape as well as the write circuit and playback circuit of the magnetic tape device, the above channel is a high speed mode switching command or a low speed mode switching command. When the magnetic tape control device receives the speed mode switching command from the channel, the magnetic tape control device immediately sends a signal to release the exclusive use of the channel by the magnetic tape device. A response signal sending unit that sends a response signal back to the channel, and upon receiving the speed mode switching command, reads the status information of the status control circuit and moves the magnetic tape to a position determined by the nature of the speed mode switching command and the content of the status information. 1. A magnetic tape system comprising: a positioning control section for controlling the magnetic tape system. 2. When the positioning control unit receives a low-speed mode switching command, it moves the magnetic tape so that the magnetic head is positioned in the inter-block gap before the next data block to be read/written. A patent claim characterized in that the magnetic tape is configured to perform control to move the magnetic tape a certain distance in a direction determined by status information when a high-speed mode switching command is received. The magnetic tape system according to item 1.