JPS6017141B2 - multiple controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multiplex control device, and more particularly to a multiplex control device that enables high-speed data transfer by being connected to a plurality of disks having a low data transfer rate.

In a multiplexer channel, one channel controls a plurality of input/output devices in a time-sharing manner, so a plurality of channel programs are operated in parallel.

This multiplexer channel includes a byte multiplexer channel that multiplexes byte units, and a disk device A block multiplexer channel (IBM Corporation A22-697) that performs multiplexing in blocks to control relatively high-speed input/output devices such as magnetic tape devices
m/370 to 4mMS$tem/360andSys
1/0 1nteMace Channel to
ControlUnit Original Eq
uipment Manufacture'sinf
(see ``option''). The block multiplexer channel uses multiple processing to absorb ineffective time such as disk device seek operations and rotation waits, thereby making effective use of the channel.

For example, in a disk device, 1 & hS or 2
It takes about 10 hS, and the access time is 20 hS to 25 mS, resulting in an invalid time of 23 hS to 33 hS when the seek time and rotation waiting time are combined. On the other hand, the data transfer time is 1
/2 track takes 8 hS, and 1'4 track takes 4 mS, so for example, in order to absorb 33 mS of invalid time per disk, if data transfer time is 4 mS, 1
It is sufficient to connect eight (=33/4) disk devices to each channel. On the other hand, even if you try to increase the data transfer rate by connecting multiple devices with low data transfer rates as described above, in the conventional block multiplexer channel, one device is used as the channel and control unit during data transfer. data transfer rate cannot be increased by multiplexing. By the way, the channel is C
When the start 10 command is received from the PU, the main memory C
The disk drive number and track number are read from the start address indicated in the CW area and sent to the control device, which decodes these numbers and sends them to the corresponding disk device.

In that case, first, a specific track is called with a seek command, a specific sector is searched with the next set sector command, and the key or record number is referenced with a search command.
Data is read with the last read command. Note that when a track number or a seek command is sent from a channel to a control device, a channel end is notified to the channel, thereby releasing the occupation between the channel and the control device and setting it in a free state.
Further, when all processing is completed and head movement is completed, the device end is reported from the control device to the channel. Note that conventional control devices only have a small buffer memory of 1 to 2 bytes to absorb speed variations, and commands from the channel are decoded and transferred to the device as is, and read or write data is is being relayed as is. Traditional block multiplexers like this
In order to increase the data transfer rate between the channel and the control device in the channel, a method of increasing the capacity of the buffer memory and multiplexing is also being considered.

However, for example, in the case of a read operation, a read command is issued from the channel, the data read from the device is read into the buffer memory of the control unit, and after some data has been accumulated in the buffer memory, the channel and control Even if a method is used to transfer data between devices at high speed and in a short time, in a block multiplexer channel, the channel end is sent back from the control device to the channel as a status byte in response to a read command from a certain device. Until then, no commands can be issued to other devices from the channel. Therefore, even if a buffer memory is provided in the control unit to reduce the pure data transfer time between the channel and the control unit, it only reduces the time for reading or writing to a single device; The effective data transfer cannot be multiplied by multiplexing devices.The purpose of the present invention is to solve these conventional problems by:
To provide a multiplex control device capable of increasing the data transfer rate per channel to multiple times the data transfer rate of a single device when a plurality of devices are connected to one block multiplexer channel. It is in. In order to achieve the above object, the multiplex control apparatus of the present invention connects controlled devices individually and controls data transfer between the block multiplexer channel and the controlled devices. 1 corresponding to the control device
Equipped with a data buffer that stores the amount of data transferred once,
When a pre-read command is received from the above channel,
．． It is characterized in that the channel end is immediately returned to release the channel occupancy, and data is previously transferred from the controlled device to the data buffer before receiving the read command.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a multiplex control device showing an embodiment of the present invention.

The multiplex controller 3 is connected to the block multiplexer channel 2, and the lower part has a low data transfer rate (150K).
n devices 8 are connected.

Although n is an arbitrary integer, it is assumed here to be eight. The device 8 is an information recording device in a computer system, and is a magnetic disk drive device, an optical disk drive device, etc., but here it is assumed that it is an optical disk drive device with a low data transfer rate.

The multiplex control device 3 includes a microprogram control section 4, a channel interface control section 5, and data buffers 6-0 to 6-1 (n) corresponding to optical disk drives to be connected.
-1), and a device interface control section 7.

The optical disk drives 8-0 to 8-(n-1) are equipped with high-speed data buffers 9-0 to 9-(n-1) of small capacity (for example, about 51.2 bytes). in this way,
The multiplex controller 3 of the present invention is provided with a data buffer 6 corresponding to the connected device, and also transfers data from the device to the data buffer 6 in advance as a command between the channel 2 and the multiplex controller 3. A new pre-read command will be provided to instruct that the As a result, a plurality of optical disk devices with slow transfer speeds are connected, time division multiplexing control is performed from one block multiplexer channel, and data transfer is performed at a data transfer rate higher than that unique to the optical disk device. FIG. 2 is an operation time chart when data is read from devices 810 and 811 by time division multiplex control in the multiplex control apparatus shown in FIG. First, when only the optical disk 810 is connected to the multiplex control device 3 and data is read to the CPUI, the C
The PUI issues a pre-read command and a read command through a command chain.

The preread command specifies the address where the data to be read exists and the number of bytes to read. Second
As shown in FIG.
“After transmitting zero status bytes and receiving the location of the data to be transferred and the number of bytes read, the second
As shown in FIG. b, after transferring the channel end in response to the preread command of the device 8-0 and releasing the channel, the designated device 8-01 issues a positioning command and starts executing the preread.

At this point, the multiplex controller 3 becomes free. Figure 2c
As shown in FIG.
Read 512 bytes of data into the first stage of 0. Device 8 Ichikawa reports to the multiplex controller 3 that data has been read into the first stage of the high-speed data buffer 9-0, and then takes over and reads the data into the second stage of the high-speed data buffer 9-0. . When the multiplex controller 3 receives a report from the device 8-0 that the high-speed data buffer 910 is full, it reads the data into the data buffer 6-0. The transfer speed at this time is about 10 times the device-specific reading speed (here, 15 disk bytes/sec).
Here, it is 1.9 Mbytes/sec). When the first stage data buffer is finished reading, the multiplex controller 3 becomes free, and when the second stage data buffer becomes full, the multiplex controller's data buffer 6 is read again.
-0 and data buffer 9-0 of device 8-0. At this time, data is being read from the device 9-O into the first stage of the data buffer 9-0 at the same time. In this way, when the number of bytes specified by the pre-read command has been read into the data buffer 610 in the multiplex control device 3, the multiplex control Device 3 connects device 8 to block multiplexer channel 2.
-0 Returns the device end of the preread command. Channel 2 is the device for pre-read commands.
When the end is received, the command chain executes the next read command. As shown in FIG. 2h, when the multiplex control device 3 receives a read command from the device 8-0, the multiplex control device 3 transfers the data between the channel 2 and the data buffer 6-0 of the control device 3, as shown in FIG. 2i. Transfer data between devices at high speed. Note that the data buffer 610 has sufficient capacity to store the number of bytes transferred by one read command. When the data transfer is finished, the second
As shown in Figure i, device 810 sends the channel end and device end of the read command back to channel 2. In this way, when reading data from only one device, each data transfer between data buffers 910 and 610 and between data buffer 610 and channel 2 becomes faster, but multiple transfer processing is not performed, the effective data transfer rate is not improved. Next, when writing data from the CPU to only the optical disk 8-0, a prewrite command and a write command are issued using a command chain, as in the case of reading.

In the prewrite command, the device 8101 is positioned using the same method as before.

That is, the position on the optical disk 8-0 where data is to be written and the number of written bytes are sent from the channel 2 to the multiplex control device 3. The multiplex control device 3 performs prewrite/
When the command is received, the status byte of “0” is transferred. Next, when the write position and number of write bytes are received, the channel end status byte is transferred, and after releasing the occupation of channel 2, the specified A positioning command is issued to the device 8-0.

At this point, the multiplex controller 3 becomes free. Once the positioning is complete, device 8-0 reports to multiplex controller 3, which forwards the device end to channel 2 as a status byte. This operation is
Conventionally, this method has been known as a seek multiplex method and a rotational position detection method. Channel 2 issues a write command upon receiving the device end of the prewrite command. Data transfer takes place between channel 2 and data buffer 610 of multiplex controller 3. Data Buffer 6 - River When the transfer to the other is completed, the multiplex controller 3 transfers the channel end to channel 2. Next, the multiplex control device 3 transfers the data in the data buffer 6-0 to the high-speed data buffer 9 in the optical disk device 8-01.
10 first and second stages at high speed. When the high-speed data buffer 9-0 becomes full, the transfer is interrupted and the multiplex controller 3 becomes free. When the data is stored in the optical disk device 8-Kawama and data buffer 9-01,
Start writing. When the first stage data buffer becomes empty, a data transfer request is made to the multiplex controller 3. The multiplex control device 3 transfers data from the data buffer 6-0 to the data buffer 9-0 of the optical disk device 810. By repeating the above sequence, when all data has been written, multiplex control unit 3 transfers the device end to channel 2. Next, a plurality of optical disk devices 8-0 to 8-
The case where (n-1) is supported will be explained with reference to FIG.

In this case, by providing a pre-read command, high-speed multiple data transfer processing during reading becomes possible. That is, if you want to perform read processing on devices 8-10 and 8-1 at the same time, first, as shown in FIG.
Issue a command.

When the channel end of the preread command for device 810 is returned in FIG.
1, the device 8-
Issue a pre-read command for 1. Figure 2c
and device 8-0 or 8 as shown in FIG.
11, the multiplex controller 3 transfers the device interface to the corresponding data buffer 6-0 or 6-1 in the order of which data is first filled in the data buffers 9-10 and 9-1 in the optical disk device. Data is taken in via the control unit 7. The device interface control unit 7 is used for the devices 8-0 and 8-1 in a time-sharing manner. When either one of devices 8-10 and 8-1 finishes transferring all data to the data buffer, multiplex controller 3 issues an interrupt request to channel 2. In Figure 2, since the data of device 8-0 has been read first, the second
The device end for the pre-read command of device 810 is transferred to channel 2, as shown by the arrow from FIG. 2c to FIG. 2g.

In response, channel 2 issues a read command for device 8-0 as shown in FIG. 2, data is transferred at high speed. When the data transfer is completed, the channel end and device end shown in FIG. 2i are returned. As shown in Figure 2 i,
While data is being transferred between data buffer 6-0 and channel 2 in multiplex control device 3, other data buffers 6-0
1 to 6-(n-1) are devices 8-0 to 8-(n-1)
As shown in FIG. 2f, data transfer is performed in parallel from the device 8-1 to the data buffer 6-1.

In FIG. 2i, when the read command for device 8-0 is completed, the connection between channel 2 and multiplex control unit 3 becomes free, so at this time pre-reading of device 8-0 is executed, that is, device 8-0 is read. If reading from the device 8-1 to the data buffer 6-1 has been completed, at this point, as shown in FIG. The end will be returned.

Channel 2, on the other hand, as shown in FIG.
Issues a read command and reads data from multiplex controller 3.
Data is transferred from buffer 6-1 to channel 2 at high speed (see FIG. 2m). Finally, as shown in FIG.
1 read command channel end, device
The end will be returned. Note that even when data is written to a plurality of optical disk devices by multiple processing from the CPU, the operation is performed in the same manner as described above.

In this way, when using the multiplex control device 3 shown in FIG.
By connecting devices 8-0 to 8-1 (n-1), the data transfer rate per unit time for channel 2 can be increased approximately 7 to 8 times.

Note that the multiplex control device 3 in FIG.
Data buffer 6-0 that can store the amount of data transferred
61 (n-1), but if each device is provided with a data buffer sufficient to store the amount of data transferred at one time, the data buffer 6 of the multiplex control device 3
It is also possible to exclude -0 to 6-(n-1). As explained above, according to the present invention, when a plurality of devices are connected to one flock multiplexer channel, the data transfer rate per channel is multiple times the data transfer rate specific to the device. Therefore, it is extremely effective when simultaneously transferring data in an optical disk device or the like with a slow transfer rate.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a multiplex control device showing an embodiment of the present invention;
FIG. 2 shows a time diagram of multiple control operations showing an embodiment of the present invention.
It's a chat. 1: CPU, 2: Block multiplexer channel, 3: Multiplex controller, 4: Microprogram control, 5
: Channel interface control unit, 6-0 to 6-(n
-1): data buffer; 7: device interface control section; 810 to 81 (n-1): controlled device; 910 to 91 (n-1): small capacity data buffer. Figure 1 Figure 2

Claims (1)

[Claims] 1. A multiplex control device that connects a plurality of controlled devices and transfers data between them and a block multiplexer channel, which is equipped with a data buffer that stores the amount of data transferred at one time for each controlled device. , returning the channel end by receiving a pre-read command from the block multiplexer channel;
A multiplex control device characterized in that the channel is released from occupation and data is transferred from a designated controlled device to a corresponding data buffer before receiving a read command from the channel.