JPS61251252A - Processing method for data transfer - Google Patents

Abstract

PURPOSE:To exhaustively input data inputted continuously from outside equipments with a limited buffering capacity by transferring all of inputted data which are buffered until a receiving time of an instruction to a central processing unit against a Read instruction from a host central processing unit. CONSTITUTION:With the inputting of the data to an input/output device 1 from an outside device 14, the first one bite is stored at the preceding buffer which an input pointer 18 points out and also an input pointer is updated and an interrupt request is issued against a central processing unit 2. With receiving the interrupt request from the input/output device 1, the central processing unit 2 instantly issues the Read instruction to the input/output device 1. A microprogram 9 which receives the Read instruction in the input/output device 1 stores the value of the input pointer at that time at an input pointer work and transfers the receiving data which are existed from an effective data preceding address within buffer which is pointed by an output pointer to the receiving data which are stored at the input pointer work in an administration table to the central processing unit 2.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a data transfer processing method, and in particular, to a buffering control method for data continuously input from an external device, in which data input is prevented from being missed. A method for controlling data transfer to upper main memory that is suitable for

[Background of the invention]

Conventionally, in data transfer processing between a central processing unit and intelligent peripheral input/output devices, the data input method for data input from an external device is based on a data input command ( Read-command) allows input from an external device, reads the input data into the buffer according to the number of input data words accompanying the command, and when the input data from the external device reaches the requested number of input words, the input data is transferred to the main memory of the upper central processing unit. There are two types of data transfer processing methods: a data transfer processing method in which the data input request means is similar to the method described above, but has multiple buffers, and allows continuous input of data by performing alternating buffer control. .

In the former method, data is input from the external device only after receiving an input command from the central processing unit, so data input from the external device is interrupted from the completion report after data input is completed until the next data input command is received. Therefore, there is a drawback that data that is input continuously is temporarily lost until the next Read command. In addition, the latter method compensates for the above-mentioned drawbacks and enables continuous input by alternately controlling multiple buffers, but the memory capacity increases due to holding multiple buffers.
Furthermore, when data processing by the central processing unit is performed in 1-byte units, the number of input requested words is 1 byte and continuous requests are made, so the buffer is switched every time 1 byte is transferred, making alternating buffer control less effective. In addition, since the control for alternating buffer control is complicated, it takes time to switch buffers, and during that time there is a possibility that a buffer may be temporarily lost.

[Purpose of the invention]

An object of the present invention is to provide a data transfer processing method between a central processing unit and an Intellishade input/output device, in response to an R6ad instruction from a higher-level central processing unit. By transferring the input data to the central processing unit, the buffer is free for a long time, thereby eliminating the buffer full state. An object of the present invention is to provide a data transfer processing method that allows data to be input without losing data at a high capacity.

[Summary of the invention]

The data transfer processing method of the present invention focuses on the fact that data output from an external device connected to an input/output device occurs asynchronously with a data read request issued from a central processing unit. A processing method that previously controlled data input from an external process in synchronization with a data read request issued from a data read request is made independent of data input control and data output control, and data input and data output are processed asynchronously. When a data read request is made from the central processing unit, all input data that has been buffered up to the time of the data read request is transferred to the central processing unit, thereby creating a large amount of free buffer space.

[Embodiments of the invention]

An embodiment of the present invention will be explained below with reference to the drawings.

FIG. 1 shows an example of the configuration of a computer system to which the present invention is applied. The input/output device 1 is connected to a serial loop bus 4 controlled by the l0P3, and data is exchanged with an external device 14 under the central processing unit 2, which mainly includes a BPO 4, a main memory 6, and a system bus 7. Performs input/output control.

An input/output device 1 equipped with an MPU 5 operates according to a microprogram 9 and has a bus interface device IO for inputting and outputting data to and from the central processing unit 2 via a serial loop bus 4.

A transmission buffer and a reception buffer for temporarily storing input/output data, and their management information t'iR and AMII are secured, and the external device 14 and the input/output device 1 communicate with the microprogram via the line 13 and the line interface device 12. Data input/output is performed from 9Vc.

FIG. 2 shows details of the RAM II in FIG. 1, and shows a reception buffer 15 and a reception buffer management table 16 in an embodiment to which the present invention is applied.

First, the central processing unit 2 issues an initialize command to the input/output device 1ic. When the microprogram 9 that controls the input/output device 1 receives this instruction, it changes the input pointer 18 and output pointer 17 of the buffer management table 16.
After storing the start address 20 of the receive buffer 15 in
Start line interface device ff112 and connect external device 1.
Waits in a state ready to receive data from 4.

When input/output device l/\ data is input from the external device 14, the reception processing of the micro program 9 first stores the first byte in the buffer pointed to by the input pointer 18, and at the same time stores the input point 1. The controller 18 is updated and an interrupt request is issued to the central processing unit 2. From the second byte onwards, buffering and updating of the input pointer 18 are repeated unconditionally according to the input pointer 18.

Immediately upon receiving an interrupt request from the input/output device 1, the central processing unit 2 issues El and ead commands to the input/output device IK.

The microprogram 9#'i of the input/output device 1 that receives the Read command stores the value of the input pointer 18 at that point in the input pointer work 19, and outputs the received data at the starting address of valid data in the batza pointed to by the output pointer 17. The received data from to the address stored in the input pointer work 19 of the management table 16 is sent to the central processing unit 21C.
By transferring, all received data up to the time when the Read command is received will be transferred to the central processing unit 2. During this time, the data input from the external device 14 is executed as is, the data is continuously buffered according to the input pointer 18, and the received data is transferred to the central processing unit 2 from the data input from the external device 14. Of course, it is also much faster. Subsequently input data is transferred to the central processing unit 2 by the next Read command, and the buffer becomes empty each time, so the buffer never becomes full.

According to this data transfer processing method, there is no buffer full state, so it is possible to easily buffer input data from an external device without overflowing it with a limited buffer capacity.

In the figure, 21 is the buffer last address.

Note that FIG. 3 is a flowchart of a microprogram for buffering received data, and FIG. 4 is a flowchart for a microprogram for transferring received data to the central processing unit.

〔Effect of the invention〕

According to the present invention, it has become possible to receive continuous data sent by an external device without missing it, thereby increasing the efficiency of data transfer between the external device and the central processing unit via the intelligent input/output device. will improve.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a computer system according to an embodiment of the present invention.
Figure 2 is a detailed diagram of the RAM in Figure 1, Figure 3 is a flowchart of a microprogram that buffers received data, and Figure 4 is a flowchart of a microprogram that transfers received data to the central processing unit. .

Claims (1)

[Claims] 1. Data transfer between the main memory of the central processing unit and the intelligent input/output device is performed by a serial data loop bus, and the transmission method on the loop bus is a packet transmission method. In the data transfer processing method for the intelligent input/output device that cannot transmit data continuously and indefinitely, a data read request from the central processing unit is made for data that is continuously input from an external device. A buffer with a memory capacity that will not overflow even if there is a temporary delay, an input pointer from an external device for managing valid data in this buffer, and an output pointer for transfer to the main storage device are provided. . A data transfer processing method, characterized in that when a data read request is made from the central processing unit, all data input from an external device up to the time of the request is transferred, and a buffer is always emptied after the data transfer process.