JPH04157699A - Preliminary writing method for flash erasure-type e2 prom - Google Patents

Abstract

PURPOSE:To enable waiting time to be reduced by finding a memory region to be erased by patrol before erasure and then performing preliminary writing at a non-written part of the memory region at a preliminary writing processing part. CONSTITUTION:A patrol timer 11 sends out an interrupt request (IRQ) to a CPU 10 at a certain time interval and a patrol processing part 13 is started when it is accepted, thus enabling a flash erasure type E<2>PROM 12 to be patrolled. The, when a memory region to be erased is found before erasure, a preliminary writing processing part 14 is started immediately and preliminary writing processing is performed. This erasure is performed to a last write bit within the memory region are in write-enable state when this processing ends. In this manner, performing preliminary writing processing in dispersion eliminates the need for performing collective preliminary writing immediately before erasure and enables waiting time when performing preliminary writing to be reduced.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Prior art (Figures 4 and 5) Means for solving the problem to be solved by the invention (Figure 1) Example (Fig. 2, Fig. 3) Effect of the invention [Summary] Regarding the writing method of the batch erasing type E2PROM, it is possible to shorten the waiting time by distributing and processing the preliminary writing performed before erasing the flash E2PROM. In the preliminary writing method performed before batch erasing of a batch erase type E2PROM (flash E2PROM) that can electrically write and erase data at once, the batch erase type E2PROM is
The OM is patrolled at certain intervals during periods when there is no memory access. Through this patrol, the memory area to be erased is found before erasing. If the memory area to be erased is found, the corresponding memory area is detected. The configuration is such that all bits of the memory area to be erased are brought into a written state by performing preliminary writing to the last written portion of the memory area.

[Industrial application field]

The present invention relates to a writing method for self-erasable E2PROM,
More specifically, the batch erase type E2P ROM, that is,
A rewritable FROM that electrically writes and erases all at once (hereinafter referred to as "Franche E2PROM")
In particular, the present invention relates to a write method for a self-erasing type E2PROM that improves the preliminary writing process performed before bulk erasing.

[Conventional technology]

4 and 5 are diagrams showing a conventional example, in which FIG. 4 is an explanatory diagram of file management, and FIG. 5 is a write processing flowchart.

In the figure, 1 is a memory card (IC card), 2 is a flash E2PROM element, and 3 is a file management area.

In recent years, flash E2PR has become a type of E2PROM.
CM development is actively underway. In the future, such flash E2PROM will be used as E"PROM, EPROM,
It is seen as promising as a replacement element for SRAM and the like.

However, the flash E2PROM is prone to over-erasing due to its cell structure. Over-race is when a written cell and the last written cell are erased at the same time, the last written cell becomes over erased and the data cannot be written at the next writing. It means not being able to do it.

In order to prevent such overwriting, when normally erasing a file, the file is not actually erased, but only a flag indicating that the file has been erased is set in the header or file management information called a disc libter.

Files are organized when the file storage area is used up, but in flash E2PROMs, preliminary writing is required before erasing the written information.

Therefore, at the stage of organizing the files described above, the memory area to be erased must first be brought into a state where all bits are written.

The conventional write process will be explained in detail below with reference to FIGS. 4 and 5. Note that each process number in FIG. 5 is shown in parentheses.

For example, file management in a memory card using Franche E2PROM is as shown in FIG.

In this example, memory card 1 is connected to 8 flash E2P
It is constructed using a ROM (memory element) 2. A file management area 3 is provided in a part of these eight flash E''P ROMs 2 as a memory area for file management.

This file management area 3 contains file management information (flags, etc.) called header or disk printer.
This is used as a storage area for.

Data written to memory car F'1 is normally managed in file units (file #1 to file #4), and management information for each of these files (file location,
data write status, flags, etc.) are collectively stored in the file management area 3.

Also, to erase memory card 1, use Franche EtPRO.
This can be done in M units (chip units), and after deletion, the files are organized.

The preliminary write process performed before this erase process is performed as follows.

First, in a memory card system, when there is a processing instruction from the outside (SL), if the processing is "reading" of data (S2), then the data reading processing is executed (S3), and the "r writing processing" is executed. If there is (S2), data writing processing is performed (S4).

However, if the content of the process is "deletion" (S2), the deletion flag of the header or disc libter in the file management area 3 is turned on to "for example 1" (S5) without actually performing the deletion process. .

After that, the above process is repeated until there is an instruction to organize the files, and when there is an instruction to organize the files (S6),
The deletion flags in the file management area 3 are checked, and if there is a flag that is turned on, preliminary writing is performed for that file (S7).

This preliminary writing is to change all bits in the corresponding file to a written state for all bits to which nothing has been written.

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

[Problem to be solved by the invention]

The above-mentioned conventional devices had the following drawbacks.

[1] Preliminary writing processing to prevent overwriting involves writing to the last writing focus for all bits in the memory area to be erased. Conventionally, this writing processing was performed all at once. ing.

Therefore, the processing time for preliminary writing becomes longer (usually 1
(about 2 seconds per megabit).

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

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such conventional drawbacks and to shorten waiting time by distributing and processing preliminary writing performed before erasing a flash E2PROM.

[Means to solve the problem]

FIG. 1 is a principle diagram of the present invention, in which 1o is a CPU;
11 is a patrol timer, 12 is a sticky erasing type E"PR,
OM (Fura Noche E"PROM), 13 indicates a patrol processing section, and 14 indicates a preliminary write processing section.

In order to achieve the above object, the present invention has developed a self-erasable E2PROM in which data can be electrically written and erased all at once.
(Flash E2PROM) In the preliminary writing method performed before the batch erasing of 12, the batch erasing type E2PROM
In contrast to 2, the patrol processing unit 13 performs patrol after a certain period of time when there is no memory access,
Through this patrol, a memory area to be erased is found before erasing, and when a memory area to be erased is found, the preliminary write processing unit 14 performs preliminary writing to the last written part of the memory area, thereby All bits in the memory area to be erased are in a written state.

[Function] Since the present invention is configured as described above, it has the following effects.

From the patrol timer 11, the CPU is
Issue an interrupt request <IRQ) for 0.

When this interrupt request is accepted (during a time period when there is no memory access, etc.), the patrol processing unit 13 is activated and patrols the batch erase type E2PROMI 2.

If a memory area to be erased before erasing is found in this patrol, the preliminary write processing section 14 is immediately activated to perform preliminary write processing.

This preliminary writing process is performed on the last written bit in the memory area to be erased, and when this process is completed, all bits in the memory area to be erased are in the written state.

In this way, by patrolling at regular intervals,
If the preliminary write processing is performed in a distributed manner, there is no need to perform the preliminary write all at once immediately before erasing, as is the case in the past.

Therefore, the waiting time required for preliminary writing as in the prior art can be reduced.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

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

In the figure, the same reference numerals as in FIG. 1 indicate the same parts. Also, 15
indicates a program storage unit, and 16 indicates a flash E2PROM card.

This embodiment is an example of a flash E2PROM card system. The Flash E"F ROM card system includes a Flash E"F ROM card 16,C
PUl0, patrol timer 11, patrol processing unit 1
3. A preliminary write processing section 14, a program storage section 15, etc. 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 receives the interrupt request from the CPU
It is activated when it is accepted (permitted) by O, and finds the file to be erased by patrolling the flash E2PROM16. That is,
By patrolling, flags in the file management area 3 (see FIG. 4) are checked to find files to be deleted.

The preliminary write processing unit 14 is activated when a file to be erased is found during patrol by the patrol processing unit 13, and performs preliminary write processing (setting the last written bit to a written state) on the file to be erased. .

The flash B2PROM16 has a configuration as shown in FIG. 4, for example, and a part thereof is provided with a file management area.

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

Next, a preliminary writing method for the flash E2PROM in the flash E2PROM card system having the above configuration will be explained based on FIG. Note that each process number in the figure is shown in parentheses.

File processing in the flash E2PROM card system is performed as shown in FIG. 3A.

First, when the CPU10 receives a processing instruction from the outside (Sll), it determines the content of the process (522), and if it is data "reading", it reads the data from the Fra Noche E"PROM card 16 (523). ), if the data is "written", the data is written to the flash E2PROM 16 (S14).

In addition, if the instruction is to "delete", the header in the file management area in the Fra Noche E"PROM16,
Alternatively, turn on the deletion flag for the corresponding file in the disk librator (make it a to be deleted state) (S1
5). If such processing is repeated and files are organized, <316) and -batch deletion is performed (S17).
, then perform file organization such as rewriting (31B)
.

This file organization involves rewriting data in areas that are not to be erased in order to collect them in one place, and processing that collects erased empty areas.

By the way, in addition to the above file processing, in the present invention,
Patrol processing as shown in FIG. 3B is always performed, and the above-mentioned erasure processing is performed on files that have been subjected to preliminary writing processing through this patrolling.

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

When the patrol processing unit 13 is activated (S21), it patrols the flash E''PROM card 16 and checks the deletion flag of the header or disc libter in the file management area provided in a part of the card. Find out which files should be deleted.

At this time, if there are files to be deleted, nothing will be done, but
If a file to be erased is found, preliminary writing is performed.This preliminary writing process is to put all bits of the last write into a written state, as in the past (S22).
.

This process is continued until the patrol process ends (the end of the patrol process is determined in advance) and ends (323).

Note that if processing information such as preliminary writing by patrol is stored as file management information, it can be used for subsequent erasure processing and the like.

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

(1) It can be used not only for flash 22PROM cards (IC cards) but also for various types of flash E2PROM devices.

(2) The patrol time interval, etc. is determined by flash E2PR.
It may be set arbitrarily depending on the usage status of the OM.

〔Effect of the invention〕

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

+1+ Since the preliminary writing process is performed in a distributed manner by patrolling using free time, etc., waiting time can be shortened.

(2) Man-machine interface can be improved by reducing waiting time.

(3) It is possible to improve the throughput of the flash E2PROM device.

[Brief explanation of the drawing]

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 22PROM card system, and FIG. Processing flowchart (1), and FIGS. 4 and 5 are diagrams showing a conventional example. FIG. 4 is an explanatory diagram of file management, and FIG. 5 is a write processing flowchart. 10...-CPU 11-Patrol timer 12-Batch erasure type E2PROM (Flash E2PROM) 13-Patrol processing section 14--Preliminary writing processing section Patent applicant Fujitsu Limited Patent attorney Tatsuo Imamura Fludge: LE" Mr. Makita of PFZOM cart system
tj#舅tel Diagram 2 () 2nd 1 (Logic's flow-9-w-to) Diagram 3 Diagram B

Claims (1)

[Claims] Batch erasing type E^2PROM (flash E^2PROM) (12) in which data can be electrically written and erased all at once.
In the preliminary writing method performed before batch erasing, the batch erasing type E^2PROM (12) is patrolled at certain intervals during periods when there is no memory access, and by this patrol, the memory area to be erased is identified. is found before erasing, and when a memory area to be erased is found, preliminary writing is performed to the last writing part of the memory area so that all bits in the memory area to be erased are in the written state. Bulk deletion type E^2PRO characterized by
Preliminary writing method for M.