JP2614357B2 - Bulk erase type E (2) PROM pre-programming method - Google Patents

Description

[Contents] Outline Industrial application field Conventional technology (FIGS. 4 and 5) Problems to be Solved by the Invention Means for Solving the Problems (FIG. 1) Action Embodiment (FIGS. 2 and 3) Effects of the Invention [Overview] Regarding the write method of the batch erase type E ² PROM, the flash E ²
The preliminary writing performed before erasing PROM, by treating by dispersing, aims to reduce the waiting time, data electrically writing and capable of batch erasing collective erasure type E ² PROM (flash E ² In the pre-programming method performed before the batch erasing of the PROM), the batch erasing type E ² PROM is patroled at a certain time during a time period when there is no memory access, and the memory area to be erased is determined by this patrol. When the memory area to be erased is found before the erasure and the memory area to be erased is found, all bits of the memory area to be erased are written by performing preliminary writing on an unwritten portion of the memory area. .

[Industrial applications]

The present invention relates to a method of writing collective erasure type E ² PROM, and more particularly, collective erasure type E ² PROM, i.e., electrically writing, electrically rewritable PROM to erase collectively (hereinafter, this In particular, the present invention relates to a writing method of a batch erase type E ² PROM which is used for a flash E ² PROM) and in which a preliminary writing process performed before a batch erase is improved.

[Conventional technology]

4 and 5 are views showing a conventional example, and FIG.
FIG. 5 is an explanatory diagram of file management, and FIG. 5 is a flowchart of a writing process.

In the figure, 1 is a memory card (IC card), 2 is a flash
The E ² PROM element 3 indicates a file management area.

In recent years, as a kind of E ² PROM, the development of flash E ² PROM is being actively carried out. Such a flash E ² PROM
Is promising as a replacement element for E ² PROM, EPROM, SRAM, etc. in the future.

However, in the flash E ² PROM, a state of over-erasing (over-erasing) occurs due to the structure of the cell. Over lace means that if a written cell and an unwritten cell are erased at once, the unwritten cell will be in an over-erased state. It means that you can no longer do it.

In order to prevent such overrun, the file is not actually erased at the time of normal file erasure, but only a flag indicating that the file has been erased is set in the header or file management information called a descriptor.

Then, when the file storage area is exhausted, the files are organized. In the flash E ² PROM, preliminary writing is required before erasing the written information.

Therefore, at the stage of performing the above-mentioned file organization, first, the memory cells to be erased must be in a state where all bits are written.

Hereinafter, a conventional write process will be described in detail with reference to FIGS. 4 and 5. FIG. The respective processing numbers in FIG. 5 are shown in parentheses.

For example, file management in a memory card using a flash E ² PROM is as shown in FIG.

In this example, memory card 1 has eight flash E ² PROMs.
(Memory element) 2. A file management area 3 is provided in a part of the eight flash E ² PROMs ² as a memory area for performing file management.
Is provided.

The file management area 3 is used as a storage area for a header or file management information (such as a flag) called a disk printer.

The data written to the memory card 1 is usually managed in file units (file # 1 to file # 4), and the management information (file position, data write state, flag, etc.) of each file is , File management area 3
Are stored together. Further, erasing of the memory card 1 can be performed in units of flash E ² PROM (in units of chips), and after erasing, files are organized.

The preliminary writing process performed before this erasing process is performed as follows.

First, in the memory card system, when there is a processing instruction from outside (S1), if the processing is "reading" of data (S2), data reading processing is executed (S2).
3) If it is "write processing" (S2), data write processing is performed (S4). However, if the content of the processing is “deletion” (S2), the deletion flag of the header or the descriptor in the file management area 3 is turned on (for example, 1) without actually performing the deletion processing (S5).

After that, the above processing is repeated until there is a file organizing instruction. When there is a file organizing instruction (S6),
Looking at the deletion flag in the file management area 3, if any flag is ON, preliminary writing is performed for the file (S7). This preliminary writing is to put all the bits in the corresponding file in which nothing has been written into a writing state.

When the preliminary writing is completed for all areas to be erased, data erasing processing (erasing is possible in units of memory chips) is performed (S8), and thereafter, file organization such as rewriting is performed (S9).

[Problems to be solved by the invention]

The prior art as described above has the following disadvantages.

(1) Preliminary write processing to prevent over-by-race
Writing is performed on unwritten bits for all the bits of the memory area to be erased. Conventionally, this writing process is performed collectively.

For this reason, the processing time of the preliminary writing becomes longer (usually 1
About 2 seconds per megabit).

(2) The waiting time due to the preliminary writing becomes long, and the man-machine interface is bad.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional drawback and to reduce the waiting time by distributing and processing the preliminary writing performed before erasing the flash E ² PROM.

[Means for solving the problem]

FIG. 1 is a diagram showing the principle of the present invention.
Denotes a patrol timer, 12 denotes a batch erase type E ² PROM (flash E ² PROM), 13 denotes a patrol processing unit, and 14 denotes a preliminary writing processing unit.

In order to achieve the above object, the present invention relates to a preliminary write method performed before a batch erase type E ² PROM 12 capable of electrically writing and batch erasing data, wherein the E ² PROM
12 has a file management area, and when the processing content instructed to the E ² PROM 12 is a deletion (substantially the same as “deletion”), the file is not actually deleted and the file is not deleted. Deletion information indicating the state to be deleted is stored in the management area, and this process is repeated until there is an instruction to organize the files, and the E ² PROM 12 is set by the patrol timer 11 during a time period when there is no memory access. Patrol processing means (patrol processing unit 13) performs patrol at time intervals, and by checking whether or not there is deletion information in the file management area, a memory area to be deleted before batch deletion is found by this patrol. When a memory area to be deleted is found, a preliminary writing process is performed, and all bits are written to the memory area.

As described above, the file management area is provided in the E ² PROM 12, and the CPU 10 manages this file management area. Then, when a delete command or a delete command is issued, the CPU 10 sets deletion information indicating a “state to be deleted” or “erasable” in a corresponding file management area, for example, sets a flag, and actually sets The actual erasure is performed only when it becomes necessary to erase the data.

In this case, the patrol processing unit 13 has the patrol timer 11 and independently checks the flag when the predetermined time has fallen apart from the instruction of the CPU 10 and performs the actual deletion.
This is performed in advance without waiting for an instruction from the CPU 10, and this is called “patrol processing” or simply “patrol”.

Further, in the batch erasure type E ² PROM 12, “0” and “1” are mixed in a certain address data. For example, “0” is defined as an erased state, and “1” is defined as a written state (there may be the opposite definition). Therefore, if an attempt is made to erase data in a state where “0” and “1” are mixed, an operation is performed in which the data “0” is further erased in spite of the erased state. It is called an over-erased (excessively erased) state and is prohibited because it affects the reliability of the memory cell. For this reason, the preliminary write processing as described above is performed.

[Action]

Since the present invention is configured as described above, the following operation is provided.

The patrol timer 11 issues an interrupt request (IRQ) to the CPU 10 at regular intervals. When this interrupt request is accepted (a time period when there is no memory access or the like), the patrol processing unit 13 is started and patrols the batch erasure type E ² PROM 12.

When a memory area to be erased before erasing is found by this patrol, the preliminary write processing unit 14 is immediately activated to perform preliminary write processing.

This preliminary write processing is performed on unwritten bits in the memory area to be erased, and when this processing is completed,
All bits in the memory area to be erased are in the written state.

As described above, if the preliminary writing process is performed in a distributed manner by the patrol performed after a predetermined time, it is not necessary to collectively perform the preliminary writing immediately before erasing as in the related art.

Therefore, the waiting time at the time of the preliminary writing as in the related art can be reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

2 and 3 are views showing one embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a flash E ² PROM card system, and FIG. 3A is a processing flowchart (1) of the embodiment. FIG. 3B is a processing flowchart (2) of the embodiment.

In the figure, the same reference numerals as those in FIG. 1 denote the same parts. Reference numeral 15 denotes a program storage unit, and 16 denotes a flash E ² PROM card.

The present embodiment is an example applied to a flash E ² PROM card system. The flash E ² PROM card system,
Flash E ² PROM card 16, CPU 10, Patrol timer 1
1, a patrol processing unit 13, a preliminary writing processing unit 14, a program storage unit 15, and the like are provided.

The patrol timer 11 is a timer that issues an interrupt request (IRQ) to the CPU 10 at regular intervals.

The patrol processing unit 13 is activated when the interrupt request is received (permitted) by the CPU 10, and the patrol processing unit 13
A file to be erased is found by patrol in the E ² PROM 16. That is, a flag in the file management area 3 (see FIG. 4) is checked by patrol to find a file to be deleted.

The preliminary write processing unit 14 is started when a file to be erased is found by patrol by the patrol processing unit 13, and performs preliminary write (puts an unwritten bit into a write state) in a file to be erased. .

The flash E ² PROM 16 has a configuration as shown in FIG. 4, for example, and a file management area is provided in a part thereof.

The program storage section 15 stores various programs used in the card system.

Next, a preliminary writing method of the flash E ² PROM in the flash E ² PROM card system having the above configuration will be described with reference to FIG. Each processing number in the figure is shown in parentheses.

File processing in the flash E ² PROM card system is performed as shown in FIG. 3A. First, in CPU10,
If a processing instruction from the outside (S11), determines the content of processing (S22), if the "read" the data, reads data from the flash E ² PROM card 16 (S23), "write data ", Data is written to the flash E ² PROM 16 (S14). If the instruction is "delete", the header in the file management area in the flash E ² PROM 16 or the delete flag for the corresponding file in the descriptor is turned on (set to a state to be deleted) (S15). ). When such a process is repeatedly performed to perform file organization (S16), batch erasing is performed (S1).
7) After that, perform file organization such as rewriting (S1
8).

In order to organize the files, rewriting is performed to collect the data of the area not to be erased at one place, and processing of combining the erased empty areas is performed.

By the way, apart from the above-mentioned file processing, in the present invention, the patrol processing as shown in FIG. 3B is always performed, and the above-mentioned erasing processing is performed on the file which has been subjected to the preliminary writing processing by this patrol. Done.

The patrol processing is performed by activating the patrol processing unit 13 when an interrupt request issued from the patrol timer 11 at regular intervals is accepted by the CPU 10 (when permitted).

When the patrol processing unit 13 is started (S21), a patrol is performed on the flash E ² PROM card 16 to check a header or descriptor deletion flag in a file management area provided in a part of the card. Find files to delete.

At this time, if there is no file to be erased, nothing is done, but if a file to be erased is found, preliminary writing is performed. This preliminary write processing is to put all unwritten bits into a write state as in the conventional case (S2
2).

This process is performed until the patrol process is completed (patrol process completion is determined in advance), and the process ends (S23). If processing information such as preliminary writing by patrol is stored as file management information, it can be used for subsequent erasing processing and the like.

Although the embodiments have been described above, the present invention can be implemented as follows.

(1) The present invention can be used not only for flash E ² PROM cards (IC cards) but also for various flash E ² PROM devices.

(2) The patrol time interval and the like may be arbitrarily set according to the usage state of the flash E ² PROM.

〔The invention's effect〕

As described above, the present invention has the following effects.

(1) The waiting time can be shortened because the preliminary writing process is performed in a distributed manner by patrol using idle time or the like.

(2) The man-machine interface can be improved by shortening the waiting time.

(3) Throughput of the flash E ² PROM device can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIGS. 2 and 3 are diagrams showing one embodiment of the present invention, FIG. 2 is a schematic configuration diagram of a flash E ² PROM card system, and FIG. FIGS. 4 and 5 are diagrams showing a conventional example. FIG. 4 is an explanatory diagram of file management, and FIG. 5 is a flowchart of a writing process. 10 CPU 11 Patrol timer 12 Batch erase type E ² PROM (flash E ² PROM) 13 Patrol processing unit 14 Preliminary writing processing unit

Claims (1)

(57) [Claims] 1. A preliminary writing method performed before batch erasing of a batch erasing type E ² PROM capable of electrically writing and batch erasing data, comprising a file management area in a part of said E ² PROM, E ² PR
When the processing content instructed to OM is deletion (erase),
Without actually deleting the file, the deletion information indicating the state to be deleted is stored in the file management area, and this process is repeated until a file rearrangement instruction is given, and the E ² PROM is accessed for memory access. Patrol processing means performs patrol at a time interval set by a patrol timer in a non-time zone, and by this patrol, by checking whether there is deletion information in the file management area,
A batch erasing type in which a memory area to be deleted is found before the batch erasing, and if a memory area to be removed is found, a preliminary writing process is performed, and all bits are written to the memory area. E ² PROM preliminary writing method.