JPH0799491B2 - A power failure countermeasure device for a disc recording / reproducing device of a micro computer. - Google Patents

Description

The present invention relates to a power failure countermeasure device for a microcomputer disk recording / reproducing device.

[Outline of Invention]

The present invention relates to a power failure countermeasure device for a microcomputer disk recording / reproducing device, in which the values of various registers can be backed up by a backup power source when a power failure is detected.
When it is detected that the disk recording / playback device was in the write state when the power failure was detected when it was saved in the RAM and when the power failure was restored, the RAM The values of the various registers saved in the RAM are returned to their respective registers, and when the power failure is restored, it is detected that the disk recording / playback device was in the write state when the power failure is detected, and the values of the various registers saved in the RAM are saved in the respective registers. After returning to the main loop, by returning to the main loop and causing the data field that was being recorded when the power failure of the disc was detected to be rewritten from the start point, the disc recording / reproducing device writes the data to the disc. Even if there is a power failure during writing, save the data being written and write the data when the power is restored. It is obtained to be able to redo.

[Conventional technology]

Conventionally, when a power failure occurs while writing data to a disk (a magnetic disk such as a floppy disk or hard disk) by connecting a disk recording / playback device to a microcomputer, a power failure protection built in the disk recording / playback device. The device is working to stop writing the data.

[Problems to be solved by the invention]

In such a conventional technique, no protection is provided for the data being written to the disk at the time of power failure.
For example, if a power failure occurs while writing important data to a disk directory area, reading the disk directory area after the power failure will result in an error, making the entire disk inaccessible. Will end up.

In view of such a point, the present invention can save the data being written and re-write the data when the power is restored, even if a power failure occurs while writing data on the disk by the disk recording / reproducing apparatus. It is intended to propose a power failure countermeasure device for a disc recording / reproducing device of a microcomputer.

[Means for solving problems]

A power failure countermeasure device for a disk recording / reproducing device of a microcomputer according to the present invention is, as is apparent from FIGS. And a means (step ST-1) for saving the values of various registers in the RAM (4) when a power failure is detected by the power failure detecting means (8),
A means for detecting whether or not the disk recording / reproducing apparatus (6) was in a writing state when a power failure was detected at the time of power failure recovery (step ST-7), and a writing state when the disk recording / reproducing apparatus (6) was detected at the time of power failure recovery. Means (step ST-8) for returning the values of the various registers saved in the RAM (4) to the respective registers when it is detected that
When the power failure was restored, it was detected that the disk recording / playback device (6) was in the write state when the power failure was detected, and the RAM (4)
After the values of the various registers saved to are returned to their respective registers, the process returns to the main loop, and the data field that was being recorded when the power failure of the disk is detected is rewritten from the starting point. .

[Action]

According to the present invention, when it is detected that the disk recording / reproducing device (6) is in the writing state at the time of power failure detection at the time of power failure recovery, the values of the various registers saved in the RAM (4) are respectively stored. After returning to the register and recovering from the power failure, it was detected that the disk recording / reproducing device (6) was in the write state when the power failure was detected, and the values of the various registers saved in the RAM (4) were returned to the respective registers. , Returning to the main loop, the data field that was being recorded when the power failure of the disk was detected is rewritten from the starting point.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIGS. 1 to 4. First, the hardware of the present embodiment will be described with reference to FIG. (1) shows a microcomputer as a whole, which comprises a CPU (2), a ROM (3) and a RAM (4). This RAM (4) is backed up by the backup power supply (5). The microcomputer (1) further includes various registers such as a register and a stack register, but the illustration thereof is omitted.

(6) is a disk (magnetic disk) recording / reproducing apparatus, which is driven by the microcomputer (1). (7)
Is a write protection device, which is actually built in the disc recording / reproducing device (6).

(8) is a power failure detection means (device), which controls the backup power supply (5) when a power failure is detected, backs up the RAM (4), interrupts the CPU (2), and interrupts the CPU (2) as a non-maskable interrupt. At the same time, the write protect device (7) is controlled to the write stop state.

Next, with reference to FIG. 1, the function of the microcomputer (1) based on a program executed by an interrupt when a power failure is detected will be described. If a power failure occurs during execution of the main loop ML, the CPU (2) is interrupted (non-maskable interrupt) at point A of the main loop ML by the power failure detection means (8) detecting the power failure. By doing this, the values (addresses, etc.) are stored in RAM in the registers and stack registers necessary for the work being executed at point A.
At the same time as saving to (4) (step ST-1), the power supply voltage drop flag is set to 1 (flag is set) (step
ST-2).

Next, it is determined whether or not the power supply voltage of the CPU (2) has completely dropped within a predetermined time (step ST-3), and if the power supply voltage has completely dropped, the power failure recovery is awaited.

If the power failure is restored (power on) (Step STM-
4), the CPU (2) starts operating, and it is determined whether the power supply voltage drop flag is 1 (step ST-5). If the power supply voltage drop flag is 1, the process moves to the power failure recovery loop, and first, the checksum of the RAM (4) is taken to determine whether or not the power failure recovery process is possible (step ST-6). This is when the data in RAM (4) has been destroyed,
This step is provided for safety because the power recovery process cannot be performed.

If the power failure recovery processing is possible, it is judged whether or not the disk recording / reproducing apparatus (6) was writing or reproducing at the time of power failure (step ST-7), and the disk recording / reproducing apparatus (6) was writing. If so, after returning the values of the various registers saved in the RAM (4) to the original registers (step ST-8), the process returns to the main loop ML and, as shown in FIG. In the data field that was being recorded when the power failure was detected, point A when the power failure occurred
Instead, the data is rewritten (data is rewritten) from the starting point (point B).

Now, in the main loop ML, when writing data to the disc by the data recording / reproducing apparatus (6), as shown in FIG. 2, the write sector number of the disc is set (step ST-a), and then writing is attempted. The address of the RAM (4) containing the data is set (step ST-b). If a power failure occurs while writing is being performed according to the set value (step ST-c), steps ST-b and ST-c are restored after the power failure is restored.
In the middle of, the data is written again from the start point of the data field. It should be noted that since data indicating what data is to be written in which sector of the disk before the power failure occurs is left in the RAM (4), it is possible to write again.

If it is determined in step ST-7 that the data was being reproduced at the time of the power failure, the process similarly returns to the main loop ML to reread the data from the start point of the data field that was being reproduced when the power failure of the disk was detected. .

Referring back to FIG. 1 again, if it is determined in step ST-3 that the power supply of the CPU (2) has not completely dropped within the predetermined time, the process proceeds to step ST-9 and the power supply voltage drops. The flag is lowered, that is, the power supply voltage drop flag is set to 0, and then the process proceeds to step ST-10 to return the values of the various registers saved in the RAM (4) to the respective registers, and then to the main loop ML. Return to point A at the time of power failure.

In step ST-5, the power supply voltage drop flag is set to 1
If not, that is, if it is 0 or if it is determined in step ST-6 that the power failure recovery is impossible, the process proceeds to step ST-11 to initialize the RAM (4) and the voltage drop flag,
Return to main loop ML.

Further, if it is determined in step ST-7 that the disk recording / reproducing device (6) is neither writing nor reading at the time of power failure detection, the process proceeds to step ST-9 described above.

According to the present embodiment, even if a power failure occurs while data is being written to the disk by the disk recording / reproducing apparatus, the data being written can be saved and the data can be rewritten when the power is restored. . Further, according to the present embodiment, even if a power failure occurs while the disk recording / reproducing apparatus is reading the data on the disk, the data can be read again when the power is restored.

〔The invention's effect〕

According to the present invention described above, even if a power failure occurs while data is being written to the disk by the disk recording / reproducing apparatus, the data being written can be saved and the data can be rewritten when the power is restored. A power failure countermeasure device for a disc recording / reproducing device of a microcomputer can be obtained.

[Brief description of drawings]

1 is a flowchart of an embodiment of the present invention, FIG. 2 is a partial flowchart of FIG. 1, FIG. 3 is a block diagram showing hardware of an embodiment of the present invention, and FIG. 4 is a book. It is a figure with which explanation of one Example of an invention is offered. (1) is a microcomputer, (2) is a CPU, (3)
Is ROM, (4) is RAM, (5) is backup power supply,
(6) is a disk recording / reproducing device, (7) is a write protection device, and (8) is a power failure detecting means.

Claims (1)

[Claims] 1. A RAM that can be backed up by a power failure detection means and a backup power supply.
And a means for saving the values of various registers to the RAM when a power failure is detected by the power failure detection means, a means for detecting whether or not the disk recording / reproducing apparatus was in the write state at the time of power failure detection at the time of power failure recovery, and the power failure recovery At the time, when it is detected that the disc recording / reproducing device is in the writing state at the time of the detection of the power failure,
The RAM has means for returning the values of the various registers saved in the RAM to the respective registers, and when the power failure is restored, it is detected that the disk recording / reproducing apparatus is in the write state when the power failure is detected.
After the values of the various registers saved in the above are returned to the respective registers, the process returns to the main loop to rewrite data from the starting point to the data field that was being recorded when the power failure of the disk was detected. A power failure countermeasure device for a microcomputer disk recording / reproducing device.