JPS63163526A - Magnetic tape controller - Google Patents

Abstract

PURPOSE:To perform the quick processing by sending operation instruction to a magnetic tape device at intervals of a short time. CONSTITUTION:When a superior device 2 sends an command to a magnetic tape controller 1, the magnetic tape controller 1 inputs the instruction from the superior device 2 to a buffer circuit 10 and increments a counter 30. If the instruction is stored in the buffer circuit 10, an executing part 20 reads out and analyzes the instruction to output the operation instruction to a magnetic tape 3. Simultaneously, the counter 30 is decremented. An input/output control part 40 monitors overflow of the counter 30; and if overflow occurs, the magnetic tape controller 1 is set to the busy state to inhibit acceptance of instructions from the superior device 2, and the magnetic tape controller 1 is released from the busy state if overflow of the counter 30 is released by command execution in the executing part 20.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a magnetic tape control device.

(Prior Art) A conventional magnetic tape controller fi (MTC) has a host device 1 (
When it receives a command from the CPtl), it analyzes the command and sends an operation instruction to the Haki Tape i1i (MTU). Then, the magnetic tape controller MTC is kept in a busy state until the operation of the magnetic tape unit (MTU) is completed.

Exchanges between the host device CP[J, the magnetic tape controller MTC, and the magnetic tape controller MTU are performed as follows.

(11 The upper VC CPU sends a command to the magnetic tape controller MTC.

(2) The magnetic tape controller MTC analyzes the received command and installs the tape device fj! t, sends an operation instruction to the MTU.

(3) After the magnetic tape unit MTU completes its operation, it reports the completion to the magnetic tape control unit MTCK.

(4) Report on the completion of the above-mentioned magnetic tape control device MTC
sends a termination interrupt to the host CPU.

(5) The host device cPtJ checks whether it has ended normally.

The execution of the command is completed as described above, and the following (1)
) to (5) are repeated.

(Problems to be Solved by the Invention) Incidentally, the streamer type magnetic tape device using the reel direct drive method has an operational feature in that it cannot be immediately stopped within IR and G because it does not have a capstan.

However, after executing one command, if the same type j, that is, forward type or back type command, is obtained within a certain time 1i5 (IJ instruction time), tape running will continue without stopping. Because it executes the process using the same method, it can process faster than a normal capstan-driven magnetic tape device.

On the other hand, if the same type of command is not given within a certain period of time, the tape cannot be immediately stopped, so it takes time to position the tape and execute subsequent commands, slowing down the processing speed. Therefore, when a large amount of data is to be continuously saved or restored, it is desirable to continuously output commands to the magnetic tape device MTtJ within the re-instruction time.

The above-mentioned conventional magnetic tape controller MTC has a magnetic chip controller [After the operation of the magnetic tape unit MTU ends and before sending the next command to the magnetic tape unit MTU, (1) an interrupt to the host device CPU of the magnetic tape controller MTC; 2) Upper equipment e
It is necessary to perform the following operations: check the status of the magnetic tape control unit MTc of the CPU, and (3) send a command to the magnetic tape control unit MTC of the upper l1ic dragon (CPt).

Therefore, high-end equipment f! If the processing of LCP(J is delayed, there will be a situation where the magnetic tape controller MTC cannot issue a command to the magnetic tape unit MTU within the re-instruction time.

An object of the present invention is to provide a magnetic tape control device that can perform high-speed processing by sending operation instructions to the magnetic tape device at short time intervals.

(Means for solving the problem) In order to achieve the above object, a magnetic tape control device according to the present invention is provided.) In a magnetic tape control device that controls an IJ-type magnetic tape device, a buffer circuit that successively accepts instructions and stores the accepted instructions until execution is completed; an execution unit that executes the instructions in the order received by the buffer circuit; A counter is decremented each time an instruction is executed in the execution unit and indicates the number of unexecuted instructions currently accepted. When the contents of the counter match the maximum storage capacity of the buffer circuit, it is set to a busy state and It prohibits the acceptance of instructions from the device, releases the busy state when the content of the counter is smaller than the storage capacity of the buffer circuit, and allows the acceptance of instructions from the host device, and returns to the busy state when an error is detected during instruction execution. and means for generating an interrupt to the host device.

(Example) The invention below with reference to the drawings? I will explain in more detail.

FIG. 1 is a block diagram showing an embodiment of a magnetic tape control device according to the present invention.

In FIG. 1, a host device 2 is connected to a magnetic tape control device l via a bus 4. As shown in FIG. The magnetic tape device 3 is controlled by the magnetic tape control device 1.

The magnetic tape control device 1 includes a 16-word buffer circuit 10 for storing instructions from the host device 2. Execution unit 2 analyzes and executes instructions in the order of input when instructions are input to buffer time [10]
0. A 4-bit counter 3 that is incremented at the same time as an instruction is input to the buffer circuit 10 and decremented when the instruction is output to the buffer circuit 10 and the execution unit 20.
0, and an input/output controller 40 that controls the busy state of the magnetic tape controller l.

If the host device 2 is sending a command to the magnetic tape control device 1, is the magnetic tape control device 1 the host device? The command from A position 2 is input to the buffer circuit 10, and the counter 30 is fully incremented.

When the instruction is stored in the buffer circuit 10, the execution unit 20 extracts the instruction t-+a, analyzes it, and outputs an operation instruction to the magnetic tape device 3. At the same time, counter 30
is decremented.

The input/output control unit 40 monitors the overflow 'f of the counter 30, and when an overflow occurs, in other words, when the buffer circuit 10 is full, the magnetic tape control unit 1tlt is detected.
- Set to busy state and prohibit reception of commands from the host device 2. When the counter 30 is no longer over 7o- due to the execution of the command by the execution unit 20, the magnetic tape control device 1
clear the busy state.

When the operation instruction to the magnetic tape device 3 is completed, the execution unit 20 checks whether it is normal or not, and if it is normal, the next instruction is read from the buffer circuit 10.

When an abnormality is detected, the input/output control section 40 puts the magnetic tape control device 1 into a busy state, interrupts the host device 2, and reports that an abnormal event has occurred.

The host device 2 is a magnetic tape control unit [by interrupt from 1]
By reading the contents of the counter 30 along with the various statuses in the basic tape control system, it is possible to know which command caused the abnormal event.

(Effects of the Invention) As described above, the present invention allows processing for the magnetic tape control capacity of the host device to be performed while the magnetic tape device is operating by accepting the next command even when the command is being executed. A magnetic tape controller is a magnetic tape device.
This has the advantage that operation instructions can be sent out at short time intervals.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a magnetic tape control device according to the present invention. l...Magnetic tape control unit (MTC) 2...Host device (CPtJ) 3:...Magnetic tape unit (MTU) 4...Path 10...Buffer circuit 20...
Execution unit 30... Counter 40... Input/output control unit Patent applicant NEC Corporation Agent Patent attorney Inoro Jusai Figure 1

Claims (1)

[Claims] A magnetic tape control device that controls a streamer-type magnetic tape device includes a buffer circuit that successively receives a series of commands from a host device and stores the received commands until execution is completed; an execution unit that executes an instruction; a counter that is incremented each time the buffer circuit receives an instruction and decremented each time an instruction is executed by the execution unit to indicate the number of unexecuted instructions currently accepted; When the contents of the counter match the maximum storage capacity of the buffer circuit, the system is set to a busy state and commands from the host device are prohibited, and when the contents of the counter are smaller than the storage capacity of the buffer circuit, the busy state is released and commands from the host system are disabled. 1. A magnetic tape control device comprising: means for allowing instructions to be accepted; and means for setting a busy state and generating an interrupt to a host device when an error is detected during instruction execution.