JP2913954B2 - External storage controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external storage control device, and more particularly to an external storage control device for controlling an external storage device of a computer system which stores data of a minimum unit of writing and reading together with identification information in a unit storage area.

[0002]

2. Description of the Related Art An external storage control device for controlling an external storage device is provided between a host system, that is, a CPU and the external storage device, and writes data into the external storage device under the control of the host system. , Such as reading data from the external storage device.

In a magnetic disk device as a typical external storage device, a unit storage area on a magnetic disk for storing data of a minimum unit of writing and reading is called a sector, and this sector has identification information unique to the sector. And the data of the aforementioned minimum unit. The identification information includes a head number for specifying a magnetic head capable of accessing a storage surface to which the sector belongs, a track number for specifying a track on each storage surface, and a sector number given to a large number of sectors included in each track. It is composed of

When writing and reading data in the minimum unit (hereinafter referred to as unit data), the magnetic disk controller first selects a magnetic head and a track corresponding to a sector specified by the host system, and then selects the magnetic head. And instructs the magnetic disk drive to read the sector identification information from the sector at that position by driving to the track. The magnetic disk control device determines whether or not the sector number in the read sector identification information matches the sector number specified by the host system. Processing such as reading is performed, and if they do not match, the magnetic disk drive is controlled to read the identification information of the adjacent sector.

In a magnetic disk device, unit data is usually written or read to or from a plurality of sectors in at least one track by one processing request. In the conventional magnetic disk control device, first, the sector number of the start point of the processing such as writing or reading (hereinafter referred to as processing) for the track is stored in the first register in the number of the sector to be processed or the end point of the processing. The sector number is stored in the second register. The read sector number is compared with the contents stored in the first register, that is, the sector number of the processing start point, and if they match, processing is performed on that sector, and then the sector number of the next sector is read out. The disk device is controlled to update the contents stored in the first register to the sector number of the next sector. If the content of the second register is the number of sectors to be processed, the number is decremented by one.

If the read sector number does not match the stored contents of the first register, the magnetic disk drive is controlled so as to read the sector number of the next sector without performing processing for that sector.

[0007] The above-described series of control is repeated to obtain the second control.
When the number of sectors to be processed, which is the storage content of the register, becomes zero (or if the storage content of the register is the sector number of the sector at the processing end point, the read sector number matches that sector number) At this time, since the read sector number means the sector number of the sector at the processing end point, processing is performed on the sector having this sector number, and processing on the track to which these sectors belong is completed.

In this conventional magnetic disk control device, the processing is not performed until the matching of the sector number of the first register in the storage, that is, the processing start point and the read sector number is detected. Even if the read sector number is the sector number of the sector to be processed, the first
No processing is continued until the sector number of the processing start point, which is the storage content of the register, is read. For example, each track has a sector number (0) to a sector number (1).
It is assumed that the sector to be processed has sector numbers of (2) to (9), and the magnetic head is located immediately before the sector of sector number (6). The first register stores the sector number (2).
When the reading of the sector number is started, the sector number read first is (6), and therefore does not match the sector number (2) stored in the first register.
Therefore, the processing for that sector is not performed, and the sector number (7) of the next sector is read. However, since this sector number (7) also does not match the sector number (2), no processing is performed and the sector number of the next sector is read. Thus, sector numbers (8), (9), ..., (15),
The state where processing is not performed continues until (0) and (1), and processing is performed only for the sector of sector number (2).

A specific example of this type of conventional magnetic disk control device will be described with reference to the drawings.

FIG. 5 is a block diagram of a portion to be improved according to the present invention in the conventional magnetic disk control device.

Referring to FIG. 5, the magnetic disk control device includes a serial / parallel converter 3, a selector processing control unit 5b, a processing end control unit 6, and a processing control unit 7 as main components.

The serial / parallel converter 3 is inserted between a magnetic disk control device shown in the figure and a magnetic disk device (not shown), and converts a sector number and unit data exchanged between them into a magnetic disk device. The conversion is performed so as to be bit serial on the side and bit parallel on the magnetic disk controller side.

The sector processing judging section 5b has a minimum sector number ADm of a series of sectors included in one track specified by the processing request signal R / W from the host system.
before reading from the track (reset state R)
And a selector 52a for selecting and outputting an incremented sector number after the lapse of the period, and a sector number register 54a for fetching, storing, and outputting the sector number from the selector 52 in response to the discrimination number ACJ.
And the sector number ADr read from the track and output via the serial / parallel converter 3 and the sector number from the sector number register 54a, and a discrimination signal ACJ which is turned on when both coincide with each other is generated. The comparator 55 and the sector number output from the sector number register 54a have one unit of the sector read interval (for example, “1” when adjacent sectors are sequentially read sequentially, and “2” when every other sector is read). ) Is provided, and an adder 56 that outputs a sector number obtained by incrementing ()) is provided. As described above, in the sector processing determining unit 5b, before the first sector number of one track is read, the smallest sector number among a large number of sector numbers belonging to that track is stored in the sector number register 54a. When the minimum sector number coincides with the read sector number ADr, the discrimination signal ACJ is turned on, whereby the contents of the sector number register 54a are updated. That is, the sector processing determining unit 5b determines that the read sector number is equal to the minimum sector number ADmin, and that the determination signal A
When the CJ is turned on and output, the contents stored in the sector number register 54a are updated to the next sector number at the same time. Whenever the read sector number matches the sector number from this sector number register 54a, the discrimination signal ADJ is output. ON and updating of the storage contents of the sector number register 54a are repeated, and when they do not match, the discrimination signal ADJ is kept off and the storage contents of the sector number register 54a are also kept as they are.

The processing end control unit 6 controls the minimum sector number AD specified by the processing request signal R / W from the host system.
subtracter 61 that calculates and outputs the number of sectors within the processing range of the track from min and the maximum sector number ADmax.
A selector 62 for selecting the number of sectors from the subtractor 61 in the reset state (R) and otherwise selecting and outputting the decremented sector number, and a selector 62 each time the reset state and the discrimination signal ACJ are turned on. Remaining number of registers 63 for taking in, storing, and outputting the number of sectors from 62
And a subtractor 64 that outputs "1" as the number of sectors decremented from the number of sectors from the remaining processing number register 63.
And a zero detection circuit 65 that detects that the number of sectors from the remaining processing number register 63 has become zero and generates a processing end signal END. As described above, the processing end control unit 6 stores the number of sectors within the processing range specified by the processing request signal R / W in the remaining processing number register 63, and determines the number of sectors each time the determination signal ACJ is turned on. Decrement, and when the number of sectors becomes zero, the processing end signal E
ND is generated, thereby detecting the completion of processing for one track.

The processing control circuit 7 includes a processing request signal R / W,
Receiving the determination signal ACJ and the processing end signal END,
Discrimination signal A corresponding to the sector number read from the track
When the CJ is off, the sector number of the next sector is read out without performing processing for the sector of that sector number,
When the discrimination signal ACJ is on, the process for the sector of that sector number is performed, the sector number of the next sector is read, and the following operations are repeated. In response to the generation of the process end signal END, the process end signal END After performing the processing for the sector having the sector number of, the reading of the sector numbers of the subsequent sectors is stopped. This means that the processing for one track has been completed.

As described above, the magnetic disk device controlled by the magnetic disk control device operates with the processing request signal R
When the sector number read from the / W designated track matches the minimum sector number within the processing range designated by the processing request signal R / W, processing for the sector is started from the read sector number, and then processing for the sectors is performed sequentially. When the maximum sector number within the processing range is reached, the processing for that sector ends. The end is nothing but the end of processing of one track.

Next, referring to FIG. 6 showing another example of the magnetic disk control apparatus according to the prior art, this example is the same as the example of FIG. 5 except for a part of the processing end control unit 6b. Only the same reference numerals are given to the constituent elements common to 5 and detailed description is omitted.

The processing end control unit 6b receives the processing request signal R /
Maximum sector number ADm within the processing range of the track specified by W
ax is stored in the reset state (R) and output, and a processing end sector number register 68 is provided.
Maximum sector number from 8 and serial / parallel converter 3
And a comparator 69 for generating a processing end signal END in response to a match with the sector number of the read output supplied from the CPU. Except for the points described above, the example is common to the example of FIG.

FIG. 7 shows how a process on a sector on a magnetic disk is actually performed by the conventional magnetic disk controller shown in FIGS.

Referring to FIG. 7, the magnetic disk 10
0 has a plurality of tracks 101 and these tracks 1
01 is divided into 16 sectors from sector number (0) to sector number (15).

Processing request signal R / W from host system
It is assumed that the specified magnetic head is selected, moves to the predetermined track 101, and is located immediately before the sector of the sector number (6) (SHP position in FIG. 7) in an initial state before the sector number is read. The processing target sector is from sector number (2) to sector number (9) (that is, the “processing range” is from sector (2) to sector (9)),
It is assumed that the processing for these sectors is performed sequentially.
As is clear from the above description, under this condition, the sector number (2) is stored in the sector number register 54a.

Since the sector number which is read first at the start of reading of the sector number of the track 101 is (6), the comparison result by the comparator 55 becomes inconsistent, and the discrimination signal ACJ remains off. As a result, the process for the sector with the sector number (6) is not performed, and the sector number (7) is read. Since this sector number (7) also does not match the storage content of the sector number register 54a, that is, the sector number (2), the discrimination signal ACJ remains off, the processing for the sector of the number (7) is not performed, and the sector of the next sector is not performed. The number (8) is read.

As described above, the state in which processing is not performed on the sectors up to the sector number (1), that is, the sectors from the sector number (6) to the sector number (1) continues, and when the sector number (2) is read out, Coincides with the sector number (2) stored in the sector number register 54a, so that the processing for the sector with that number (2) is performed.
At the same time, the storage contents of the sector number register 54a, that is, the sector number (2) is updated to (3), while the sector number (3) of the next sector is read out, and these sector numbers are compared by the comparator 55. .

When the processing for the sectors up to the sector number (8) is completed and the sector number (9) is stored in the sector number register 54a and the sector number (9) is read, the processing end control unit 6 or 6b A processing end signal END is generated, and the processing for the track 101 ends when the processing for the sector with the sector number (9) ends.

The external storage device to which the same control as the above-described magnetic disk control device can be applied includes not only the above-mentioned magnetic disk device but also a flexible disk storage device and an optical disk storage device.

[0026]

As described above, in the conventional external storage control device, even if the head is located in the sector to be processed, the minimum sector number as the storage content of the first register (sector number register) is stored. Until the read sector number matches, the state in which the processing on the sector at the current head position is not performed continues, so that there is a disadvantage that the time required to complete the processing on one track becomes long.

An object of the present invention is to provide an external storage control device which can reduce the time required for "processing" for one track of the external storage device.

[0028]

According to the present invention, there is provided an external storage control device which designates a processing request signal from a host system.
A minimum sector number register and a maximum sector number register for storing minimum and maximum sector numbers of sector numbers belonging to one track, and a sector number read from the track being a sector number within a processing range specified by the processing request signal. A processing range detecting unit for detecting whether or not the data is stored in the two registers; and outputting the sector number from the track based on the output of the processing range detecting unit and the stored contents of the two registers. A sector processing discrimination unit that generates a discrimination signal that is off when the sector number is within the processing range and is the first read sector number from the track and is on when the second and subsequent read sector numbers are out of the processing range. When the read sector number becomes the sector number of the sector to be the last processing of the track, the processing is terminated. And a processing completion control unit for generating a signal. The external storage control device reads the sector number of the next sector without performing the processing for the sector corresponding to the determination signal when the determination signal is off, and performs the processing for the corresponding sector when the signal is on. Thereafter, the next sector number is read, and in response to the generation of the processing end signal, processing is performed on the sector corresponding to the processing end signal, and the external storage device is controlled so that reading of the sector number thereafter is stopped.

The sector processing judging section has a sector number register and a comparator, and the sector number read from the track designated by the processing request signal R / W is a sector number within the processing range and the first from the track. When the sector number is the read sector number, the next read sector number is stored in the sector number register. When the sector number is the second or later read sector number, the storage content of the register is updated with the next read sector number. Upon reaching, the minimum sector number is stored in the register, the sector number read from the track and the storage content of the register are compared by the comparator, and a discrimination signal that is turned on when both match is generated.

Further, the processing end control unit includes a remaining processing number register and a zero detection circuit, and performs the processing on the total number of sectors within the processing range before reading the sector from the track designated by the processing request signal R / W. It is stored in the remaining number register, and each time the determination signal is turned on, the stored content of this register is incremented by one.
And the zero detection circuit generates the processing end signal when the content of the register becomes zero.

Further, the processing end control section has a processing end sector number register, and when the first read sector number from the track designated by the processing request signal is a sector number within the processing range, the sector number is left as it is in the register. If the sector number is out of the processing range, the largest sector number in the processing range is stored in the same register. When the read sector number matches the storage content of this register, a processing end signal is output. Occur.

[0032]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention.

This embodiment is applied to a magnetic disk controller, and has the minimum sector number corresponding to the sector at the start point of processing for one track specified by the processing request signal R / W from the host system (eg, CPU). , A maximum sector number register for storing the maximum sector number corresponding to the sector at the end point of the processing, a serial / parallel converter, a processing range detecting section, a sector processing determining section, It comprises a processing end control unit 6 and a processing control unit 7. As is apparent from the configuration shown in the figure, the present embodiment is different from FIG. 5 in that the minimum sector number register 1, the maximum sector number register 2, and the processing range detection unit 4 are added, and This is different from the conventional magnetic disk control device.

The minimum sector number register 1 and the maximum sector number register 2 store the minimum sector number and the maximum sector number of a large number of sectors in one track processing range, respectively.

The processing range detector 4 reads the sector number ADr read from the track designated by the processing request signal R / W supplied from the serial / parallel converter 3 from the minimum sector number register 1 and the maximum sector number register 2. And the sector number ADr
Is a sector number within the processing range. Such a processing range detection unit 4 can be easily realized by combining a comparator for comparing the magnitude of the sector number with a logic gate.

The sector processing discriminating section 5 adds a unit (usually 1) of the read interval of the sector to the read sector number ADr and outputs the result. A sector number register 54 for taking in and storing when reading the first sector number of one track (timing pulse 1R), and otherwise taking in and storing and outputting the sector number in response to the ON of the discrimination signal ADJ;
A second adder 56 outputs a sector number obtained by incrementing the sector read interval by one unit to the sector number from the sector number register 54, and a first adder 56 reads the first sector number of the track (1R). The sector number from the adder 51 is selected. Otherwise, the second adder 5 is selected.
6, the first selector 52 that selects and outputs the incremented sector number from the first sector number, compares the maximum sector number from the maximum sector number register 2 with the sector number from the sector number register 54, and determines whether they match. When the initial state and the comparison result of the comparator 58 coincide with each other, the reset state is established, and when the read sector number ADr is determined to be within the processing range by the detection unit 4, Flip-flop 5 in set state
7 and the second selector 5 which selects the sector number from the selector 52 when the flip-flop 57 is set and selects the sector number from the minimum sector number register 1 when the flip-flop 57 is reset and supplies it to the sector number register 54.
3 and the read-out sector number ADr is compared with the sector number from the sector number register 54, and the discrimination signal AC that turns on when they match and turns off when they do not match.
And a comparator 55 for generating J.

Since the serial / parallel converter 3, the processing end control unit 6 and the processing control unit 7 are the same as those of the conventional magnetic disk control device shown in FIG. 5, their description will be omitted.

Referring next to FIG. 2, which is a plan view of a magnetic disk similar to FIG. 7, the track 101 of the magnetic disk 100 is divided into 16 sectors from sector number (0) to sector number (15). It is assumed that numbers (2) to (9) are designated as processing targets.

In order to describe first the case where the sector number ADr read first from the track 100 is within the processing range specified by the processing request signal R / W, the position SHP of the magnetic head in the initial state is set to the sector number (6). It is assumed that it is immediately before the sector of.

When it is detected that the sector number ADr first read from the track designated by the processing request signal W / R is within the processing range, the flip-flop 57 is set and the selector 53 is switched to the selector 52. , The selector 52 selects the output of the adder 51, and the sector number register 54 updates the stored contents. Therefore, the sector number (7) next to the first read sector number ((6) in FIG. 2, the same applies hereinafter) is stored in the sector number register 54.
Is stored in Since the sector number register 54 changes from a state in which nothing is stored to a state in which the sector number (7) is stored with respect to the first read sector number (6), the comparison result by the comparator 55 is It becomes “mismatch” and the discrimination signal ACJ remains off. Since the process is not performed on the sector with the sector number (6), the next sector number (7) is read.

Since the sector number (7) to be read next matches the contents stored in the sector number register 54, the discrimination signal ACJ is turned on, and the processing for the sector with the sector number (7) is performed by the processing control section 7. The next sector number (8) is read. The storage content of the sector number register 54 is updated to the sector number (8) by the discrimination signal ACJ.

When the same operation is repeated and the storage contents of the sector number register 54 are updated to the sector number (9) which is the largest sector number in the processing range, the flip-flop is output by the output of the comparator 58. The selector 57 is reset, and the selector 53 selects the output of the minimum sector number register 1, that is, the minimum sector number within the processing range. When the sector number (9) is read and the discrimination signal ACJ is turned on, the contents stored in the sector number register 54 are updated to the minimum sector number (2). After the process for the sector with the sector number (9) is performed, the sector number to be read is (10), so that the discrimination signal ACJ is turned off, the process for the sector number (10) is not performed, and the next sector number is not performed. Is read out. At this time, the contents stored in the sector number register 54 are not updated.

Thereafter, the same operation is repeated, and only reading of the sector number is performed until the sector number (1) is reached.

When the sector number (2) is read, the discrimination signal ACJ is turned on, and after processing of the sector of the sector number (2) is performed, the sector number (3) is read. Further, the processing range detection unit 4 controls the flip-flop 5
7 is set, and the adder 56, the selector 52,
The storage content of the sector number register 54 is updated to the sector number (3) via 53. Hereinafter, the same operation is repeated.

On the other hand, each time the discrimination signal ACJ is turned on, the number of sectors, which is the storage content of the remaining processing number register 63, decreases, and the sector number (6) is read out, and the discrimination signal ACJ
Is turned on, the number of sectors, which is the storage content of the remaining processing number register 63, becomes zero. Zero detection circuit 65 responding to this
Outputs a processing end signal END, and the processing control section 7 performs processing on the sector with the sector number (6) and then stops reading the sector number thereafter.

By the above-described operation, the processing of all the sectors within the processing range of the track designated by the processing request signal R / W is completed.
The processing for this track is completed.

When the first read sector number ADr is out of the processing range (for example, (14)), the processing range detection unit 4 resets the flip-flop 57, and the selector 53 sets the minimum sector number register 1 , Ie, the smallest sector number (2) is selected and stored in the sector number register 54.

Next, only the reading of the sector number is performed until the sector number (2) is read. The operation after the sector number (2) is read is the same as the operation for the sector within the processing range described above. When the maximum sector number (9) is reached, a processing end signal END is generated, the processing for the sector with the sector number (9) ends, and the processing for one track ends.

As described above, in the present embodiment, if the sector number first read from one track specified by the processing request signal R / W is within the processing range specified by the signal R / W, the reading is performed. Since the processing is started from the sector next to the issued sector, the time required for processing for that track can be reduced. The reason why the processing is started from the sector next to the first read sector number is that when the read sector number is transmitted to the comparator 55, the desired number is stored in the sector number register 54. This is because the sector number has not been stored yet.

Next, referring to FIG. 3, which shows a second embodiment of the present invention, the sector processing determining section 5a of this embodiment is different from the first embodiment in that the two adders 51 and 56 are used.
Is used as one adder 51, and the selector 52 selects and supplies the first sector number or the output of the sector number register 54 read from the track designated by the processing request signal R / W to the adder 51. This is the same as the first embodiment except that the output of 51 is supplied to the selection input on the set side (S) of the selector 53. That is, the second embodiment is the same as the above-described first embodiment except that the function of the adder 56 of the first embodiment is also used for the adder 51. Omitted.

The second embodiment is more advantageous than the first embodiment in that the circuit configuration can be simplified.

Next, referring to FIG. 4 showing a third embodiment of the present invention, the third embodiment is different from the processing end control section 6a in the third embodiment.
Since the configuration is the same as that of the first embodiment except for the configuration described above, the following description is limited to the description of the control unit 6a, and the description of the entire embodiment is omitted.

The processing end control unit 6a receives the processing request signal R /
Sector number A first read from track specified by W
The processing end sector number register 68 that captures, stores, and outputs Dr, and the processing range detection unit 4 recognizes that the first read sector number is within the processing range specified by the processing request signal R / W. AND logic circuit 66 that outputs a signal that is turned on when the output signal of the logic circuit 66 is on, selects the first read sector number when the output signal is on, and outputs the signal from the maximum sector number register 2 when the output signal is off. Select the maximum sector number and end the processing. Sector number register 6
And a comparator 69 for generating a processing end signal END when the sector number ADr matches the sector number from the processing end sector number register 68.
And

In the third embodiment, if the first sector number read from the track designated by the processing request signal R / W is within the processing range designated by the processing request signal R / W, the first sector is read. At the timing of the number reading, this sector number is stored in the processing end sector number register 68. No processing is performed on the sector with the sector number read first (similar to the above-described first and second embodiments).

Thereafter, the same operation as in the first embodiment described above is repeated, and when the first sector number read out is read out again, the processing end signal END is output from the comparator 69, and the sector number is output. The processing for the sector is performed, whereby the processing for one track ends.

If the first read sector number is out of the processing range, the largest sector number in the processing range is stored in the processing end sector number register 68. Subsequent operations are the same as those of the example of the conventional magnetic disk control device shown in FIG.

The third embodiment is more advantageous than the first embodiment in that the processing end control unit can be simplified.

In the third embodiment, the sector processing determining section 5 can be replaced with the sector processing determining section 5a (FIG. 3) of the second embodiment.

Although the above three embodiments take the form of a magnetic disk controller for controlling a magnetic disk, the external storage controller according to the present invention uses a different storage medium if the data configuration is common. The present invention can be applied to the control of an external storage device such as a flexible disk device or an optical disk device.

[0061]

As described above, according to the present invention, if the first read sector number of the processing request signal from the designated track is within the processing range of the processing request signal, the processing is started from the next sector. It is no longer necessary to suspend processing until reaching the minimum sector number, which was indispensable for this type of control device.
This has the effect of reducing the time required for processing per track.

[Brief description of the drawings]

FIG. 1 is a block diagram of a first embodiment of the present invention.

FIG. 2 is a plan view of the magnetic disk for explaining the operation of the embodiment shown in FIG. 1;

FIG. 3 is a block diagram of a sector processing determination unit according to a second embodiment of the present invention.

FIG. 4 is a block diagram of a third embodiment of the present invention.

FIG. 5 is a block diagram of a first example of a conventional external storage control device.

FIG. 6 is a block diagram of a second example of a conventional external storage control device.

FIG. 7 is a plan view of the magnetic disk for explaining the operation of the external storage control device shown in FIGS. 5 and 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Minimum sector number register 2 Maximum sector number register 3 Serial / parallel converter 4 Processing range detection part 5, 5a, 5b Sector processing determination part 6, 6a, 6b Processing end control part 7 Processing control part 51 Adder 52, 53 Selector 54, 54a Sector number register 55 Comparator 56 Adder 57 Flip-flop 58 Comparator 61 Subtractor 62 Selector 63 Remaining processing register 64 Subtractor 65 Zero detection circuit 66 Logic circuit 67 Selector 68 Processing end sector number register 69 Comparator 100 Magnetic disk 101 tracks

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 3/06

Claims (8)

(57) [Claims] 1. A data processing method according to claim 1, further comprising: reading and writing data to and from a storage area designated by said processing request signal in an external storage device in response to a processing request signal from a central processing unit. An external storage control device for controlling an external storage device, wherein the external storage device stores a large number of concentric storage tracks each divided into a plurality of unit storage areas each capable of storing a unit amount of the data. A storage device provided on the surface of a disk-shaped storage medium, wherein the designation of the storage area by the processing request signal is performed by specifying the storage track and the unit storage area corresponding to a start point and an end point of the processing on the track. In the external storage control device, the smallest identification number among the identification numbers of the unit storage areas belonging to the designated track specified by the processing request signal First and second registers respectively storing a maximum identification number, and the identification number read from the specified track is an identification number of a unit storage area included in a processing range specified by the processing request signal. Processing range determining means for determining whether or not the identification number read from the designated track in response to the processing range determining means is an identification number of a unit storage area included in the processing range; Is turned off when it is the first read identification number, and turned on when it is the identification number of the unit storage area included in the processing range and is the second or later read identification number from the designated track. A unit storage area discriminating means for generating a discrimination signal that turns off when the identification number of the unit storage area is not included; And a processing end control for generating a processing end signal when the identification number read from the designated track is an identification number of a unit storage area to be processed last in the unit storage areas within the processing range. Means for reading the identification number of the unit storage area belonging to the designated track in response to the processing request signal, and when the determination signal is off, without performing processing for the unit storage area corresponding to the determination signal. The identification number of the next unit storage area is read out. When the discrimination signal is on, processing is performed on the unit storage area corresponding to the discrimination signal, and then the identification number of the next unit storage area is read out. Reading stop means for responding to the processing of the unit storage area corresponding to the processing end signal and then stopping reading of the subsequent identification number External storage control device according to claim. 2. The external storage control device according to claim 1, wherein said external storage device is a magnetic disk device. 3. If the identification number read from the specified track is the identification number of a unit storage area included in the processing range and is the first read identification number from that track, the identification number is read next. An identification number register for storing the identification number, and an identification number when the identification number read from the specified track is an identification number of a unit storage area within the processing range and a second or subsequent read identification number from the track. Means for updating the identification number, which is the storage content of the number register, to the identification number of the unit storage area next to the identification number at a predetermined timing; and a unit storage in which the identification number as the storage content of the identification number register is included in the processing range. When the largest identification number among the identification numbers of the area is reached, the smallest identification number of the identification numbers is stored in this identification number register at a predetermined timing. A unit for storing the identification number read from the designated track and an identification number as the storage content of the identification number register; and a comparator for generating the determination signal that is turned on when both match. 2. The external storage control device according to claim 1, further comprising: 4. The external storage control device according to claim 3, wherein said minimum identification number is stored in said identification number register in an initial state before reading said identification number from said designated track. 5. An unprocessed number register for storing a total number of unit storage areas included in the processing range in an initial state before reading the identification number from the designated track, and each time the determination signal is turned on, 2. The processing end control means comprising: means for decrementing the count by one from the total number; and zero detecting means for generating the processing end signal when the total number, which is the storage content of the remaining processing number register, becomes zero. External storage controller. 6. When the first read identification number from the designated track is the identification number of a unit storage area included in the processing range, the identification number is stored and the unit storage area not included in the processing range is stored. If it is an identification number, a processing end identification number register for storing the largest identification number among the identification numbers of the unit storage areas included in the processing range, an identification number read from the specified track, and an identification as storage contents of this register 2. The external storage control device according to claim 1, wherein the processing end control means includes means for comparing the numbers with each other and generating the processing end signal when the numbers match. 7. A first adder for adding count 1 to the read identification number of the specified track, an identification number register for storing and outputting the read identification number from the specified track at a predetermined timing, A second adder for adding count 1 to the identification number stored in the number register, and a first comparison for comparing the identification number stored in the maximum identification number register with the identification number stored in the identification number register When the initial state and the output of the first comparator indicate a mismatch between the two identification numbers to be compared, the reset state is set, and the output of the processing range determination means is an identification number within the processing range. A flip-flop that is set to indicate that there is, and the flip-flop is set only when the identification number is the first read identification number from the designated track. A first selector for selecting an identification number from the first adder and otherwise selecting and outputting an identification number from the second adder; and a selector when the flip-flop is in the reset state. A second selector for selecting an identification number as the storage content of the minimum identification register and selecting the identification number from the first selector to supply the identification number to the identification number register when the set state is established; 4. The external storage unit according to claim 3, wherein the unit storage area determination unit includes a second comparator that compares the identification number with an identification number that is the storage content of the identification register and outputs the determination signal that is turned on when the two match. Storage controller. 8. The first and second adders are constituted by one adder, and select the identification number only when the identification number of the unit storage area is the first read identification number from the designated track. Otherwise, the first selector is constituted by circuit means for selecting and outputting the identification number as the storage content of the identification number register, and is selected when the flip-flop of the second selector is in the set state. 8. The external storage control device according to claim 7, further comprising: a unit storage area determination unit that supplies an output of said one adder to an input terminal on a side to be processed.