JPS5852248B2 - Read data length extraction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic computer comprising a central processing unit, a main memory, and an input/output device, and relates to a method for extracting the length of data read from the input/output device to the main memory.

The central processing unit reads data from various input/output devices into the main memory, but the length of the data being read may not be known in some cases.

At this time, data is read by predicting or specifying the maximum amount of data to be read, but the length of the data actually read is required at the end of data reading.

If you want to know the amount of data read, you can check the amount of data read once.◆The amount of data read each time the reading is completed is recorded in the channel status word assigned to a specific address in the main memory. It is sufficient to look at this channel state word every time the channel is completed.

On the other hand, input/output commands can issue either a single command or multiple commands in succession.

For example, a group of data on the same circuit of a large storage device can be read at once.

When you want, seek command◆ (arm movement command), search command/
It is possible to chain commands ◆ with + (positioning command on the rotational circumference), read command, search command, reading table ◆, . . . .

The reading table ◆ must specify the length of the data to be read, and if the length specified in the read command and the length of the data actually read are different, if a chain of commands is issued, the command The chain is broken and the I/O device typically issues an index, and the chained instructions following that read instruction are not executed.

Therefore, when an interruption occurs due to a read word length mismatch, there is a drawback that subsequent instructions must be reorganized and the reading table ♦ must be reloaded.

Another method is to suppress indexing due to read word length mismatch and display a display that executes chained instructions on the readout stand◆
It is also possible to add .

However, at this time, during the chained read command, for example, at the end of the third readout board ◆, the channel status word written when all the first and second readout boards are completed has disappeared. It has been replaced with information regarding the third reading stand ♦, which has completed execution.

Therefore, if this method is used, there is a drawback that only the data length of the last read platform ◆ can be determined.

The purpose of this invention is to overcome the above-mentioned drawbacks, and the purpose is to store the length of data read from the input device to the main memory in an electronic computer consisting of a central processing unit, a main memory, and an input/output device. a data length storage means, a data length write means, and a data length read command, and the data length read out is written by the data length write means into the data length storage means specified by the data length read command. This is achieved by

The figure is a configuration diagram of an embodiment of a large storage control device based on the present invention.

In the figure, 1 is an interface control unit with a channel device (not shown), 2 is a chain instruction storage unit, 3 is an instruction read register, 4 is a decoder, 5 is a data length write circuit,
6 is a read data length counter, and 7 is an interface/control unit with a large storage device (not shown).

This is also an example of an instruction stored in the chained instruction storage unit 2,
21 is a seek instruction ◆, 22 is a search instruction, 23 is a search repeat instruction, 24 is a data reading board ◆, 25 is a data length read instruction ◆ based on this invention, 26 is a search instruction, 27 is a search repeat instruction, and 28 is a read instruction. ◆, 29 is the data length read order ◆
It is.

Here, the data reading board ♦ has an address in the main memory as its operand, and is an instruction to store the read data length in this address area.

The chain command issued from the moxibustion processing device via the channel device is stored in the chain command storage unit 2 via the interface control unit 1.

The contents of this chained instruction storage unit 2 are stored in the instruction register 3 one by one.
is read and executed.

First, the seek command /+21 is retrieved and the arm position of the magnetic head is determined, and then the search command 4>22 is retrieved to determine whether the record on the rotational circumference matches the record sought by the search command. Verify.

If they do not match, the search repeat command 23 to be executed next is specified to check whether the next record matches the record being searched for.

When a record that matches the one you are looking for is found, the data reader Aj? 24 executes reading.

After the reading is completed, the length of the read data is sent from the large storage device via the interface control unit 7 to the read data length counter 6.
written to.

Next, a data length read instruction 25 based on the present invention is added to the instruction register 3.

When this data length read command ◆25 is decoded by the decoder 4, the data length write circuit 5 reads the value of the read data length counter 6 indicating the read data length, and reads the data length read command ◆25.
The data write circuit 5 writes to the address of the main memory specified by the operand section 25.

Similarly, the following chain commands are search command 26, reading table +27
, search repeat command 4>28, and data length read command 4>29 are executed.

In the above explanation, the address in the main memory is shown as the means of storing the data length in the operand of the data length read command ◆, but the location where the data length is stored is not limited to the main memory, but may also be a special register. It is also possible to specify and store it there.

In the above description, a large storage device has been described, but the input device for reading data is not limited to this, and may be a magnetic device, a paper tape reader, or any other device.

As explained above, the present invention provides data length writing means for writing the data length read from the input/output device to a specific storage means, and a data length read command ◆, and stores the data length specified by this data length read command. By writing the read data length into the data length writing means, it has become possible to read data whose read data length is unknown without breaking the command chain.

[Brief explanation of the drawing]

The figure is a configuration diagram of an embodiment of a large storage control device based on the present invention, in which 1 and 7 are interface control units, 2 is a chain storage unit, 3 is an instruction read register, 4 is a decoder, and 5 is a data length write circuit. , 6 are data length counters, and 25 and 29 are data length read commands ◆.

Claims (1)

[Claims] 1. In an electronic computer consisting of a central processing unit, a main memory device, and an input/output device, a data length storage means, a data length write means, and a data length read command for storing the length of data read from the human-powered device to the main memory device. ◆ is provided, and the read data length is written into the data length storage means designated by this data length read command by the data length writing means.
Read data length retrieval method.