JP2652037B2 - Information recording and playback method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an information recording / reproducing method for recording / reproducing predetermined information on / from an optical card based on a command from a host computer via SCSI.

[Background Art] SCSI (Small Computer System Interface) is an interface that connects a small computer manufactured by Sugart Co. of the United States and its peripheral device SASI (Small Computer System Interface).
ace) was standardized by ANSI (American National Standards Institute) X3.131-1986, and was rewritten. It handles 8-bit parallel signals, has a data transmission rate of 1.5 Mbytes / sec, and has a multi-tax system that controls up to seven simultaneously. You can do it.

The range of the interface rules defined by the ANSI is the following five points.

(1) Types of interface signals and their definitions, signal transfer timings (2) Protocols that define the operation sequence as an interface, definitions of each phase, etc. (3) Physical interface conditions such as cable specifications and connector specifications, transmission systems (4) Command system for executing various controls and data transfer of peripheral devices, command formation and function of each command (5) Status byte format for notifying the host computer of command execution results, and This is the structure of sense data that informs an abnormal state in the process.

The command system in the above (4) is as follows.

SCSI commands are divided into eight types of groups.
The first byte of the CDB is an operation code. The upper 3 bits of the operation code specify a group code, and the lower 5 bits specify a command code (code indicating a command type) for each group.

The length of the CDB is defined as follows for each group.

(1) Group 0: 6 bytes (2) Group 1: 10 bytes (3) Groups 2 to 4: Reserved (4) Group 5: 12 bytes (5) Groups 6 to 7: Unique vendor group CDBs 6 and 7 are commands that can be uniquely defined in the SCSI device.

In each command, the logical block address is such that fixed-length data blocks are continuously arranged on the logical unit.

FIG. 8 is a diagram showing a configuration example of a logical block in a hard disk device.

In FIG. 8, the data block of cylinder = 0 and sector = 0 is set to logical block address = 0, and the sector,
Each time the track and cylinder are increased by one, the logical block address is increased by one.

The advantage of logical block addressing is that the initiator (host computer) accesses the data by designating the logical block address of the first data block and the number of processing blocks, so there is no need to be aware of the physical structure. is there. Therefore, when the above-mentioned logical block addressing is used, when devices having different numbers of cylinders, tracks, and sectors are connected to each other,
It can be operated with the same software.

In SCSI, a logical unit number (hereinafter referred to as "LU
N ") to physical devices,
It may be given to a virtual device.

FIG. 9 is a diagram showing a general example of a SCSI system configuration.

As a logical unit, usually, a physical device such as a hard disk is often used as shown in FIG.

By the way, the above SCSI usually has eight logical units of 0 to 7, and can use the extended message to have 2048 logical units.

On the other hand, an optical card has thousands of tracks, and its information capacity is several megabytes. For this reason, when an optical card is used, the area of the optical card is used in accordance with the type of information, such as using the area A for the image information and the area B for the document information, depending on the application. When managed, the required information can be searched at high speed when reproducing it. Therefore,
In order to search at high speed, area division is necessary as described above.

[Problems to be Solved by the Invention] However, in the case of a SCSI system as shown in FIG. 7, when a read instruction over several hundred logical block addresses is issued from a host computer as an initiator, usually, in an optical card, To make efficient use of the bus, disconnect the SCSI bus so that other devices can use it. Then, until the buffer is full, the read operation is performed from the medium, the reselection operation is performed again, the optical card and the initiator are connected, and the read data is transferred to the initiator.

The above reselection phase usually takes the following sequence.

(1) In the arbitration phase, the optical card attempts to acquire the right to use the bus.

(2) After making the SEL signal (select signal) true in the arbitration phase, wait at least 1.2 μS before
Make the signal true, and send the initiator and the SCSI ID of the optical card itself to the bus. Thereafter, after 90 μS or more has elapsed, the BSY signal (busy signal) is set to false. After 90 μS above, the optical card should be
After the elapse of 00 μS or more, wait for a BSY response from the initiator.

(3) After recognizing that the above operation has been performed, the initiator recognizes that the self is selected in the reselection phase, and within 200 μS after detecting that the self is selected, the BSY signal is output. Make true.

The arbitration phase takes the following sequence.

(1) Wait for a bus free phase.

(2) After detecting the bus free, wait for 800 μS or more, and set the BSY signal and the data bus bit corresponding to its own SCSI ID to true within a time not exceeding 1.8 μS after the bus is free.

(3) After elapse of 2.2 μS or more after making the BSY signal and the SCSI ID true, the SCSI device compares the values on the data bus to determine the priority of the bus use right. The priority is
ID number 7 is the highest order.

(4) The SCSI device that has succeeded in arbitration and has acquired the right to use the bus waits at least 1.2 μS from the time when the SEL signal becomes true to the time when the transition to the selection phase or the reselection phase is started.

Here, for example, when a read instruction (that is, an instruction requiring a long execution time) over the above several hundred logical block addresses is issued to a device having a low ID number, if the bus is disconnected and then reselection is attempted, the ID number is low. Therefore, arbitration often fails.

For this reason, the optical card has a problem that a loop that attempts to reselect is repeated forever.

In the present invention, the ID is transmitted from the host computer via SCSI.
To provide an information recording / reproducing method capable of avoiding a loop in which reselection continues to fail after a bus is disconnected when a relatively long time command is issued to an optical card having a low number. It is the purpose.

Means for Solving the Problems In order to avoid an infinite loop on the optical card side, that is, a loop that repeats reselection, the present invention limits the number of times reselection is repeated. It is a free phase.

[Operation] The present invention limits the number of times reselection is repeated, and if the number of reselections fails, the optical card enters the bus free phase, so that an abnormal loop on the optical card is avoided, and subsequent access to the optical card is performed. Becomes possible.

Embodiment First, the basic configuration of an optical card and the configuration of an optical head will be described. The same members are given the same numbers.

FIG. 2 is a plan view showing an example of an optical card used in the present invention.

FIG. 3 is an enlarged view of a portion indicated by A in FIG.

The optical card 1 has a linear tracking track 5 (5
−0, 5-1, 5-2,...) Are arranged at equal intervals. The data recording unit 4 (4-0, 4-1, 4-4) for recording information between adjacent tracking tracks.
2,...) Are provided. That is, the optical card 1
Has a data recording section 4 in all of the space between one tracking track and an adjacent tracking track.

As shown in FIG. 3, a G mark 7 is provided between the tracking tracks 5-1 and 5-2. This G
The mark 7 is a mark for determining a reference track, and is arranged at a predetermined location on the optical card 1 by preformatting. On the extension of the data recording unit 4 where the G mark 7 exists, a medium type pattern 8 as an auxiliary data unit
Are preformatted or recorded with light spots. The medium type pattern 8 indicates the identification of the optical card 1, and records information such as a modulation / demodulation method, a data capacity per track, and the total number of tracks.

FIG. 4 is an explanatory diagram relating to a configuration of an optical head unit of the information recording / reproducing apparatus.

FIG. 5 is an explanatory diagram showing a light beam applied to the optical card 1. FIG.

FIG. 6 is a diagram showing a configuration of a photodetector in the above embodiment.

A light beam generated by a light source 27 such as a semiconductor laser is collimated by a collimator lens 28 and divided into three beams by a diffraction grating 30. These light beams are imaged by the objective lens 26 on the tracking tracks 5-1 and 5-2 of the optical card 1 and the data recording section 4-1 as shown in FIG. 4, for example, and the beam spots S1, S2, Form S3. Here, the optical card 1 is moved in the direction of the arrow R shown in FIG. 4 by a driving means (not shown), and the optical card 1 is scanned by the beam spots S1 to S3 in the direction extending the tracking track.

The reflected light from the beam spots S1, S2 and S3 is
Again, is reflected by the beam splitter 20, and is projected by the condenser lens system 21 to the photodetectors 22, 23, and 24, respectively. The condenser lens system 21 is an astigmatism system, and performs autofocus by a known astigmatism method. These photodetectors 22 to 24 are arranged in the arrangement shown in FIG. 7, and the photodetector 23 is divided into four parts A, B, C and D.

The prism 29 shown in FIG. 4 is a prism that converts the cross-sectional distribution of the collimated light beam emitted from the semiconductor laser from an ellipse to a circle.

 Next, an operation of recording information on the optical card 1 will be described.

For example, when information is recorded in the data recording unit 4-1,
First, the beam spots S1, S2, and S3 are irradiated on the tracking track 5-1, the data recording unit 4-1, and the tracking track 5-2, respectively. These beam spots are
As the optical card 1 moves, scanning is performed in the direction of arrow F shown in FIG. The reflected light from beam spot S1 is a photodetector
22 and the reflected light from beam spot S3 is a photodetector
24, and a tracking signal is detected by a so-called three-beam method.

That is, when the beam spots S1 and S3 deviate from the tracking tracks 5-1 and 5-2, the photodetectors 22 and 24 are shifted.
The tracking signal is obtained by comparing the signals from the light receiving surfaces (tracking tracks 5-1 and 5-2). On the basis of this tracking signal, tracking means (not shown in FIG.
The beam splits S1, S2 and S3 are moved in a direction perpendicular to the scanning direction (D shown in FIG.
Direction), and automatic tracking (AT) is performed.

Then, along the tracking tracks 5-1 and 5-2, the data recording unit 4-1 is formed by the beam split S2.
The recording bit 31 is recorded accurately.

Next, a processing method in the case where the execution time is long in the present invention will be described.

When the instructions of the host computer are executed by the optical card, some operations take a relatively long time. For example, when reading several megabytes of data, the optical card starts operating with one command, but it takes a relative time to read all the data. In addition, a seek operation for moving the head position may be performed halfway, and even if this time is about several milliseconds, it can be said that a SCSI bus operating at 1.5 Mbytes / second is a relatively long time. .

In such a case, disconnection is performed, the bus is released, and another device can use the bus. Reselection is performed when the optical card completes the command or when data transfer becomes possible again.

If this reselection operation is set to, for example, up to five times, if the reselection is successful within five times, the next operation is performed. However, if the reselection has failed five times, the BSY signal is set to false in order to terminate the reselection operation and set the bus free phase thereafter.

On the optical card side, the command execution is terminated, and information indicating termination due to reselection failure is set in the eighth and subsequent bytes of the extended sense data.

FIG. 1 is a flowchart showing the operation of the above embodiment.

First, receive the command and interpret it (S1,
S2) If the process takes a long time (S3), disconnect the bus (S4) and execute the interpreted command (S4).
5) The maximum failure count value of reselection is set to 5 (S6), and reselection is performed (S7). If the reselection fails (S8), the count value is decremented by one (S11), and the reselection is performed again (S8).
7).

If the count value becomes 0 in S12, that is, if the reselection has failed five times, the bus is set free (S13). Thus, a loop in which reselection continues to fail can be avoided.

On the other hand, if the reselection succeeds before the reselection fails five times (S8), the following operation is performed (S14).
If the time for executing the command is short (S3), the command is executed (S21), and the operation proceeds to the next operation (S22). S2
When the command is executed at 1, the execution time is short, so that the bus is not set free and the number of reselection failures is not counted.

In the above embodiment, the number of reselections is set to five, but may be set to a number other than five.

[Effects of the Invention] According to the present invention, when a command that takes a relatively long time is issued from a host computer to an optical card with a low ID number via SCSI, reselection fails after the bus is disconnected. This has the effect that a loop that continues to be performed can be avoided. This also has the effect of promoting the use of a bus with good consistency in a SCSI bus having functions including disconnection and reselection, and improving the throughput of the entire system.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an operation at the time of reselection in one embodiment of the present invention. FIG. 2 is a schematic plan view showing an example of the optical card. FIG. 3 is a partially enlarged view of a portion A in FIG. FIG. 4 is an explanatory diagram relating to a configuration of an optical head unit of the information recording / reproducing apparatus. FIG. 5 is an explanatory diagram showing a light beam irradiated on the optical card. FIG. 6 is a diagram showing a configuration of a photodetector in the above embodiment. FIG. 7 is a diagram showing a configuration of a general SCSI system in which two host computers are connected. FIG. 8 is a diagram showing a general configuration example of a logical block in a hard disk device. FIG. 9 is a configuration diagram of a general SCSI system. 1 ... optical card, 4,4-1,4-2 ... data recording section, 5,5-0-5-2 ... tracking track.

Claims (1)

(57) [Claims] 1. An information recording / reproducing method in an information recording / reproducing apparatus for recording information on an optical card or reproducing information from the optical card based on a command from a host computer via a predetermined interface bus. When the information recording / reproducing device receives a command that requires an operation of accessing the optical card from the host computer, the connection between the information recording / reproducing device and the host computer is temporarily disconnected to release the interface bus. Reconnecting the information recording / reproducing apparatus and the host computer to restart the once disconnected connection after performing an access operation to the optical card in response to the received command; A reselection stage to attempt the operation; If the reconnection operation with the computer fails a predetermined number of times, a bus release step of terminating the reconnection operation between the information recording / reproducing device and the host computer in the reselection step and releasing the interface bus. An information recording / reproducing method, comprising: