JPS6275859A - Input and output control system - Google Patents

Abstract

PURPOSE:To reduce the long redundant time and to improve the processing capacity with an input/output control system by giving no actuation to an input/ output controller in case an instruction is given to a channel word for a chain command and reading out this instruction word to give an instruction to the input/output controller for start of the sequence when the preparatory is through. CONSTITUTION:A data channel device judges in its closing sequence 130 that the contents of a channel instruction word CCW show a chain command and then decides in process 132 that the chain command is equal to A to shift the sequence to a process 140. In the process 140 a channel command word CCWB is read out and the end of preparatory is informed to an input/output controller when the preparatory is through with the transfer of data. Both the data channel device and the input/output controller proceed to the transfer sequences 120 and 220 to a command B to start their processes when the input/output controller decides the end of preparatory. In the closing sequence of the command B the data channel device receives the state information from the input/output controller in a process 131 and informs the end of the transfer of data to a central processing unit by an interruption since the word CCW contains no instruction for the chain command.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an input/output control method for controlling data transfer between an input/output control device having a predetermined command sequence and a data channel device.

[Background of the invention]

Startup sequence and transfer sequence for commands or data transfer between the data channel device and the input/output control device specified by the channel command word.

A conventional control method when there is a chain command will be described in the input/output control method using the control and termination sequence.

When a data channel device receives an input/output command from a higher-level central processing unit, it confirms that the previous state of the input/output control device specified by the input/output command was normal. This confirmation is performed by reading the channel word CHW from the storage device.

When normality is confirmed, the channel command word CCW is then read from the storage device and the input/output control device specified by the input/output command is activated. Then, the device number, command, and status information DST of the input/output control device are mutually confirmed by sending and receiving transfer data (the above is called a startup sequence).
.

When normality is confirmed in the startup sequence, data is transferred between the input/output control device and the data channel device, and the data channel device transfers data between the storage device and the input/output control device (see above). When the data channel device or input/output control device detects the end of data transfer, which is called a transfer sequence, the human output control device sends status information DST to the data channel device indicating that the data transfer has ended. When the state information DST indicating the end of transfer is received, this state information DST and the channel status are sent.

The state information C8T, the word counter at the end of transfer, command address information, etc. are edited and stored in the storage device as a channel state word C8W and a channel word CHW. Furthermore, the data channel device notifies the central processing unit that sent the input/output command that the data transfer has ended (the above is called a termination sequence).

As a method for sequentially executing multiple commands for one input/output control device, there is a method in which the central processing unit detects an interrupt notification of the end of data transfer and then sends the input/output command again to the data channel device. In addition, the following methods have been commonly used. This is a method of adding a chain command directive to the channel command word CCW. That is, in the termination sequence, the data channel device determines whether there is a chain command instruction in the channel command word CC before storing the channel status word C8W in the storage device. If there is no chain command instruction, the above-mentioned termination sequence is processed, and if there is a chain command instruction, control is performed to the startup sequence without storing the channel status word C8W in the termination sequence or interrupting the central processing unit. Return. At this time, the channel command word CCW is stored at the address next to the previously executed channel command word in the main memory, and the interrupt to the central processing unit is the termination sequence of the channel command gccw when there is no chain command instruction. Let's do it. This reduces the load on the central processing unit.

By the way, depending on the type of input/output control device.

Some chain commands have a fixed sequence of commands. For example, when a command person is activated by an input/output command, command B is always designated as a chain command.

In the input/output control method of such an input/output control device, naturally, the input/output control device also processes command B after completing the processing of command A.
is known to be chained. For this reason, it is redundant to notify the input/output control device in the startup sequence as described above, and the command A
Immediately after the status information DSTe is received in the termination sequence and the normality is confirmed, the status information D is sent again in the startup sequence of command B.
There is also little need to perform ST 82. In other words, in an input/output control device where the sequence of commands issued by the chain command is fixed, the startup sequence of the commands at the end of the chain is redundant, and in input/output control methods that require high processing capacity, wasted processing time. There was the problem of being held accountable.

[Purpose of the invention]

The purpose of the present invention is to solve the problems of the prior art described above,
Chain Command An object of the present invention is to provide an input/output control method that reduces the redundant time of the activation sequence of chain destination commands in a human output control device in which the sequence of commands issued is fixed, and improves the processing capacity.

[Summary of the invention]

In the present invention, if a chain command instruction is always included in a channel command word, the data channel device reads the chained command word without starting the input/output control device during the activation sequence of the chained command, and transfers data. The input/output control device is instructed to start the transfer sequence when preparations for the transfer sequence are completed.

Therefore, the problems of the prior art described above are solved, and the redundant time of the sequence can be reduced and the processing capacity can be improved.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a diagram showing a chain configuration of channel command words CCW to be executed by a data channel device and an input/output control device. When a channel command word having the chain configuration shown in FIG. 1 is received, the second command B is always chained after the first command A, and there is no need to judge whether the command B is present or not. Incidentally, many of the recent logic devices employ a microprogram control method, and there are no features in the circuit configuration, and the key point of the present invention is the transition of the control sequence. For this reason, the operating arm of the data channel device, input/output control device.

For clarity, only the control flowchart is used.

FIG. 2 is a flowchart showing sequence transitions in a data channel device. In FIG. 2, reference numeral 110 is the activation sequence described above, reference numeral 120 is a transfer sequence, and reference numeral 130 is a termination sequence. Also, code 1
40 is a sequence 1 for reading chained command B and preparing for data transfer without restarting the input/output control device when executing chained command B. Reference numeral 131 is an identification process for determining the presence or absence of a chained command. , and the code 1
52 is a process for identifying whether the chain command method is a conventional chain command or a chain command A in which command B is always chained, which is the object of the present invention.

FIG. 3 is a flowchart showing sequence transitions in the input/output control device. In FIG. 3, reference numeral 210 is a startup sequence, reference numeral 220 is a transfer sequence, and reference numeral 230 is a termination sequence.

Further, reference numeral 231 is a process of determining a command A that is a target of the present invention, predicting that the next chained command in the case of command A is command B, and preparing to transfer this command B. . Additionally, numeral 262 determines completion of process 140 in the data channel device, i.e., process 140
This is an identification process that waits until the process is completed.

Next, the input/output control procedure will be explained using the above-mentioned flowchart.

When an I/O command is issued by the central processing unit, the data channel device is activated. The data channel device then reads the channel command word CCWA (FIG. 1), and both the data channel device and the input/output control device control startup sequences 110 and 210, respectively. Then, transfer sequences 120 and 220i are executed, respectively, and one termination sequence 150 and 260 are started, respectively. Here, the input/output control device determines command A in process 261, predicts that the next command to be chained will be command B, performs command preparation, and moves the sequence to process 252 after completing the preparation.

Meanwhile, the data channel device has its termination sequence 130
In step 131, it is determined that the content of the channel command word CCW is a chain command, and in step 132, the chain command is determined as chain command A, which is the subject of the present invention.
It is determined that this is the case, and the sequence moves to process 140.

The chain command method is determined in process 132 based on a predetermined specific pattern of status information DST returned from the input/output control device. In other words, it is possible only in the input/output control device to determine whether command B is always chained to a certain command, that is, whether that command is command A, and whether or not the next command B is chained. If this is known, that is, if it is determined that it is command A, then in step 262, status information of a predetermined specific pattern is returned to the DSTe data channel device.

◇ The data channel device reads the channel command word CCWB (FIG. 1) in process 140, and after completing the preparation for data transfer, notifies the input/output control device that the preparation is complete. and,
In step 232, the input/output control device determines whether or not there is a notification of completion of preparation, and when it is determined that the preparation is complete, both the data channel device and the input/output control device move to transfer sequences i20 and 220 for command B, respectively, and perform processing. In the termination sequence of command B, the data channel device:
Since there is no chain command instruction in the channel command word CCWB, the status information DST is sent from the input/output control device by process 131.
After receiving the data, the central processing unit that issued the input/output command is notified of the end of the data transfer by an interrupt. On the other hand, there were a lot of people.

In the force control device as well, it is predicted in process 261 that no other command is chained to command B, and after returning the normal status a information DST, the sequence is returned to a state in which a new command is accepted.

〔Effect of the invention〕

According to the present invention, it is possible to reduce the redundant time of the activation sequence of a chain destination command in an input/output control device in which the chain command sequence of commands is fixed, and to improve the processing capacity. In other words, in the conventional activation sequence of commands for both chains, the input/output control device is activated, which takes several tens of microseconds, whereas in the present invention, the input/output control device is not activated, so it takes several microseconds. It will be shortened to .

[Brief explanation of drawings]

FIG. 1 is a chain configuration diagram of channel command words that are the subject of the present invention executed by a data channel device and an input/output control device, and FIGS. 2 and 3 are sequence diagrams of a data channel device and an input/output control device, respectively. 2 is a flowchart according to an embodiment of the present invention in FIG.

Claims (1)

[Claims] In an input/output control method in which commands or data transfer between a data channel device specified by a channel command word and an input/output control device are controlled by a startup sequence, a transfer sequence, and a termination sequence, a chain command instruction is added to the channel command word. If there is always a chained command activation sequence, the data channel device reads the chained command word without activating the input/output control device, and when the preparation for data transfer is completed, the data channel device reads the chained command word without starting the input/output control device. An input/output control method characterized by instructing the start of a transfer sequence.