JPH0454525A - Spool control system - Google Patents

Abstract

PURPOSE:To reduce the possibility of occurrence of the conflict in transmission of data by providing a high speed/small capacity buffer memory in parallel to a low speed/large capacity external storage. CONSTITUTION:A high speed/small capacity buffer memory 2 is provided in parallel to a low speed/large capacity external storage 1. The data received from a host computer 3 are written into the memory 2 and therefore can be instantaneously used. If a terminal equipment 4 has a fault and the data processing speed of the equipment 4 is extremely deteriorated, the memory 2 overflows immediately owing to its small capacity. Under such conditions, the subsequent received data are written in the storage 1. When the memory 2 has the free area, the data written in the storage 1 are outputted again to the equipment 4 via the memory 2 in the output order of the data. Thus the occurrence of conflict is suppressed and the smooth transmission of data is attained.

Description

[Detailed Description of the Invention] [Summary] A spool control method that can prevent contention from occurring as much as possible, eliminate wasted processing time such as time delays due to cueing operations, and perform smooth data transmission. In the spool control method, data from the host computer is written to an external storage device and then output according to the request of the terminal device. Buffer memories are installed in parallel, and data received from the host computer is written into the buffer memory and output in response to a request from a terminal device.When the buffer memory overflows, subsequent received data is written to an external storage device. The received data is read from an external storage device when the buffer memory becomes empty, and is outputted via the buffer memory in response to a request from a terminal device.

[Industrial application field]

The present invention relates to a spool control method, and more particularly to a spool control method that uses a low-speed, large-capacity external storage device and a high-speed, small-capacity buffer memory.

[Prior art]

The data processing speed of equipment controlled by computer data (e.g. NC controlled equipment) or terminal equipment such as printers and display devices that print or display computer data is the data transmission speed transmitted from the computer via a line. It may be slower than . At this time, if a terminal device that requires data from the computer is directly connected to the computer, it will take a long time for one terminal device to monopolize the line, resulting in a large amount of time loss.

Therefore, as shown in FIG. 5, a spool control method is adopted in which data from the host computer 3 is once written into an external storage device 1, and then the data is transmitted from the external storage device to the terminal device 4.

This spool control method is applicable not only when the data transmission speed and the processing speed of the terminal device are different as described above, but also even when the data transmission speed from the host computer 3 and the data processing speed of the terminal device 4 are about the same. It is used to complement the following situations. In other words, when multiple lines are connected to the host computer, depending on how busy the host computer 3 is (how many lines are in use),
If the data transmission speed (frequency) from the host computer 3 differs, and if multiple terminals are connected to the - line, the above-mentioned Similarly, the data transmission speed (frequency) is different. In such a case, the terminal device 4 side performs the above-mentioned
A spool control method is used to accommodate temporal speed fluctuations. Furthermore, the receiving side may lose received data (
For example, if the terminal device is a printing device, paper jams,
If a spool control method is adopted even in the event of a problem (occurring due to a ribbon jam, operator error, etc.), the spooled data can be reused without having to receive it again from the host computer 3 when the problem is resolved. This makes it possible to improve processing speed without placing a burden on the host side.

[Problem to be solved by the invention]

In the conventional spooling method described above, in order to be able to deal with the various cases mentioned above, it is customary to use a large-capacity storage device such as a magnetic disk device, and to reduce costs, a relatively low-speed storage device is usually used. A storage device is used. Therefore, for example, if a write request from the host computer 3 side and a read request from the terminal device 4 occur simultaneously, a scramble for the read head will occur, and after one head writes on a track for a short time, another head will write on another track. There is a disadvantage that there are many unnecessary movements such as moving to read data from the computer, and that it takes time.

If the data transmission speed from the host computer 3 and the data processing speed of the terminal device 4 are about the same, a high-speed, small-capacity buffer memory is used as the external storage device 1 to prevent the occurrence of contention as described above. However, in this case, when data processing becomes impossible due to a failure on the terminal device 4 side, it is necessary to use the data from the host computer again, which imposes a burden on the host side. will be applied.

This invention was proposed in view of the above-mentioned conventional circumstances, and it is possible to prevent conflicts from occurring as much as possible, eliminate wasted processing time such as time delays due to cueing operations, and perform smooth data transmission. The purpose is to provide a spool control method.

[Means to solve the problem]

In order to achieve the above object, the present invention employs the following means. That is, in the spool control method in which data from the host computer 3 is once written to the external storage device 1 and then output in response to a request from the terminal device 4, as shown in FIG. A small-capacity, high-speed buffer memory 2 is installed in parallel, and while data received from the host computer 3 is written to the buffer memory 2 and output in response to a request from the terminal device 4, the buffer memory 2 overflows. Occasionally, the subsequent received data is written to the external storage device 1, and when there is "empty space" in the buffer memory 2, the external storage device 1 is written.
The received data is read out from the buffer memory 2 and outputted in response to a request from the terminal device 4.

The buffer memory 2 is provided with a standby queue 22 for temporarily storing received data and a use queue 23 for outputting data in response to a usage request from the terminal device 4, and the received data is temporarily written to the standby queue 22. After that, if there is “space” in the usage queue 23, the usage queue 23 is
If there is no "empty" space in the use queue 23, the data is input to the external storage device l.

[Effect]

By first writing the data received from the host computer 3 into the buffer memory 2, this data becomes available for immediate use. If the data transmission speed from the host computer and the data processing speed of the terminal device are approximately the same, data will be transmitted to the terminal device 4 only via the buffer memory 2. If a failure occurs on the terminal device 4 side and the data processing speed of the terminal device 4 is significantly delayed, the capacity of the buffer memory 2 is small, so it immediately overflows. At this time, the subsequent received data is written in the external storage device 1, and when there is "free space" in the buffer memory 2, the data written in the external storage device 1 is transferred to the terminal device 4 via the buffer memory 2. The data is output again in the order in which it should be output.

The buffer memory 2 is provided with a standby queue 22 for temporarily storing received data and a use queue 23 for outputting data in response to data usage requests from the terminal device 4. Data is directly input to the use queue 23 via the standby queue 22 when there is an empty space in the use keys 1-23, and is output to the terminal device 4. When there is no “space” in the usage queue 23,
The data is once input from the standby queue 22 to the external storage device 1, and then transferred to the use queue 23 after waiting for its turn, and then output to the terminal device 4.

[Example] Fig. 1 is a diagram explaining the principle of this invention, Fig. 2 is a block diagram showing an embodiment of this invention, and Figs. 3 and 4 are flow diagrams showing the procedure for implementing this invention. be.

The buffer memory 2 is provided with a reception queue 21 that serves as a window for receiving and receiving data transmitted from the host computer 3. (also processed in the above unit) are written to the standby queue 22.

When writing to this standby queue 22, first, newly received data is written to the standby queue 22.
It is examined whether or not there is space (FIG. 3, F31). If there is space in the standby queue 22, it is directly transferred to the reception queue 2.
1 data is written to the standby queue 22 (FIG. 3F)
31→F36). If there is no "empty space" in the standby queue 22, it is next examined whether the external storage device 1 is already in use (FIG. 3, F31-F32).
is in use, the data at the head of the standby queue 22 is written to the external storage device 1 via the write queue 25, the standby queue 22 is opened, and the receive queue 21 is stored in this part.
New data from F32-F in Figure 3 is written.
33-F36).

If there is no "empty space" in the standby queue 22 and the external storage device 1 is not in use, it is further examined whether there is "free space" in the use queue 23 (F32→F34 in FIG. 3). , if there is no space in the use queue 23, the queue 22 is sent to the standby queue 22 via the write queue 25 in the same way as above.
After the first data of is stored in the external storage device 1 to create an empty space in the standby queue 22, the data in the receive queue 21 is written to the standby queue 22 (F34-F33→F3
6). Furthermore, when there is "empty space" in the use queue 23, the head data of the standby queue 21 is written to the use queue 23, and after creating "free space" in the standby queue 22, the data in the reception queue 21 is written to the standby queue 23. (F34→F35→F36).

The data written to the buffer memory 2 and external storage device 1 in this way is read out as follows. That is, when there is a usage request from the terminal device 4, if data is written in the usage queue 23, the data is read out in order from the head of the usage queue 23 and sent to the terminal device 4.
(F41-F47 in Figure 4). Usage queue 2
When there is no data in 3, it is first examined whether or not the external storage device 1 is being used (FIG. 4, F41→F
42). If the external storage device 1 is used here, a continuous data group will be written to this external storage device 1 (Fig. 3 F31→F32→F33→F
36), this data group is sequentially transferred to the use queue 23 via the read queue 24, and responds to the use request from the terminal device 4 (see Fig. 4, F42→F43→F44→
F47). If the external storage device I is not in use, it is further determined whether there is data in the standby queue 22 (FIG. 4, F42→F45). Here, the waiting queue 22
If there is data, the first data in the standby queue 22 is moved to the use queue 23 in order to respond to the request from the terminal device 4 (F45 → F46 → F47).
If there is no data in the standby queue 23, the process returns to the first step (F45:N).

As a general example, the access time for a magnetic disk used as the external storage device 1 is about 50 x 104 seconds, and the access time for a large-capacity semiconductor external storage device is 1.
The buffer memory 2
The access time of a small-capacity semiconductor storage device used as a computer is about 50 x 101 seconds, which is an order of magnitude faster. Therefore, in the above configuration, the data processing speed of the terminal device 4 and the data transmission speed from the host computer 3 are about the same. If there is no failure on the terminal device 4 side, or if the transmission speed from the host computer 3 becomes extremely slow for some reason, data is written without going through the external storage device 1 (see Figure 3). F31→F36 or F31-F
32→F34→F35-F36) or can be read (see Fig. 4, F41→F47 or F41
→ F42 → F45 → F46 → F47), the access time of buffer memory 2 is very fast as mentioned above, so even if a read request and a write request occur almost simultaneously, one of the operations may be delayed due to contention. You will almost never have to wait. Conversely, if a problem occurs on the terminal device 4 side and data processing becomes temporarily impossible, the data will be written to the external storage bag f1, and in order to use the data in the external storage device 1. As in the past, although it takes some time, the data written to the external storage device 1 can be used as is, so there is no need to transmit the data again from the host computer.

〔Effect of the invention〕

As explained above, this invention uses a high-speed, small-capacity buffer memory as memory used in the spooling method, which is attached to a low-speed, large-capacity external storage device. This makes it possible to transmit data using only the buffer memory of the controller, and the possibility of contention occurring becomes extremely small.

Furthermore, even if a failure occurs on the terminal device side and data processing becomes temporarily unavailable, the data is written to the external storage device, so there is no burden on the host computer.

[Brief explanation of drawings]

Fig. 1 is a diagram explaining the principle of this invention, Fig. 2 is a block diagram of an embodiment of this invention, Figs. 3 and 4 are flow diagrams showing the procedure for carrying out this invention, and Fig. 5 is a conceptual diagram of a conventional example. It is a diagram. In the figure, 1... External storage device, 2... Buffer memory, 3... Host computer, 4... Terminal device, 22... Standby queue 23... Use queue Conceptual diagram of the present invention. IIl! + Conventional example conceptual diagram No. 58! l

Claims (1)

[Scope of Claims] [1] A spool control method in which data from a host computer (3) is once written to an external storage device (1) and then output in response to a request from a terminal device (4), comprising: A small-capacity, high-speed buffer memory (2) is installed in parallel with the external storage device (1), and the host computer (3) is connected to the buffer memory (2).
When the buffer memory (2) overflows, the subsequent received data is written to the external storage device (1) and output in response to a request from the terminal device (4). 2) A spool characterized in that when there is a gap in the spool, the received data is read from the external storage device (1) and outputted via the buffer memory (2) in response to a request from the terminal device (4). control method. [2] A standby queue (22) for temporarily storing received data in the buffer memory (2), and a terminal device (4)
Usage queue (23) that outputs data in response to usage requests
After writing the received data to the standby queue (22), if there is "empty space" in the usage queue (23), input it as is to the usage queue (23), and write " If there is no free space, connect the external storage device (1
2. The spool control method according to claim 1, wherein the spool control method is inputted into the spool control method.