Memory rewriting apparatus

• US 5,694,538 A
• Filed: 12/08/1995
• Issued: 12/02/1997
• Est. Priority Date: 03/30/1995
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Oka, Noriyuki, Okazaki, Katsuyoshi, Kisibe, Takasi, Ota, Takeo
• Primary Examiner(s): Canney, Vincent P.
• Application Number:
  US08/569,944
• Time in Patent Office: 725 Days
• Field of Search: 395/182.04, 395/182.13, 395/182.14, 395/182.15, 395/183.17, 395/183.18, 395/600, 371/10.2, 371/10.3
• US Class Current: 714/15
• CPC Class Codes: G06F 11/1433 during software upgrading

Abstract

When a rewriting instruction, which designates a specified rewriting bank is received, a rewrite processing unit copies data of the rewriting bank into a backup bank and, thereafter, writes new data prepared in a work memory such as an RAM or the like and clears the backup bank after completion of the writing operation. In this instance, flag information indicating whether data is valid or invalid is set into a plurality of banks of a flash memory. A restarting process after the writing process was interrupted is recovered by checking the flag information in all of the banks before the start of the rewriting operation and by executing the rewriting process from the beginning or in the middle of the process.

Claims

1. An apparatus for rewriting a memory, comprising:

a memory which is constructed by a plurality of banks and can be rewritten on a bank unit basis;

a first bank allocated to at least one of said plurality of banks as a backup bank;

rewrite processing means for copying data of a second bank into said first bank when a rewriting instruction is received, for writing new data into said second bank after that, and for clearing said first bank after completion of said writing operation; and

flag setting means for setting flag information indicating whether the data is valid or invalid into said plurality of banks.

2. An apparatus according to claim 1, wherein said flag setting means sets an invalid flag in an initial state or a copy erasing state and sets a valid flag in a backup state in which the data has been copied with respect to said first bank, and said flag setting means sets an invalid flag in an initial state or an erasing state and sets a valid flag in a data writing state with respect to said second bank.

3. An apparatus according to claim 2, wherein at the start of the rewriting operation, said rewrite processing means checks the flag information in each of said banks, and only when all of the banks excluding said first bank are valid, said rewrite processing means starts the rewriting process, and when any one of the banks is invalid, said rewrite processing means finishes the process as an abnormality.

4. An apparatus according to claim 2, wherein said rewrite processing means checks the flag information in all of the banks before the start of the rewriting operation, and when the second bank is valid and the first bank is also valid, said rewrite processing means copies the data of said second bank into said first bank and writes new data after that and also clears said first bank after completion of the writing operation.

5. An apparatus according to claim 2, wherein said rewrite processing means checks the flag information in all of the banks before the start of the rewriting operation, and when the second bank is invalid and the first bank is valid, said rewrite processing means writes new data into said second bank and clears said first bank after completion of said writing operation.

6. An apparatus according to claim 2, wherein said rewrite processing means checks the flag information in all of the banks before the start of the rewriting operation, and when the second bank is valid and the first bank is invalid, said rewrite processing means clears said first bank.

7. An apparatus according to claim 1, wherein after completion of the data writing, copying, or clearing of each of said banks, said rewrite processing means verifies the data in the bank and executes a next process after it was confirmed that said data is normal.

8. An apparatus according to claim 1, wherein when the data of said second bank is copied into said first bank, said first processing means stores information indicative of a backup source.

9. An apparatus according to claim 1, wherein when a rewriting instruction is recognized by a processor, in a state in which a rewriting program is loaded in said work memory of the same bank by executing a rewrite activating program stored in a specified bank in said memory, the program is executed by said processor, thereby realizing the processes of said rewrite processing means and said flag setting means.

10. An apparatus according to claim 1, wherein a certain specified bank among said plurality of banks in said memory is set to a rewrite inhibition bank, an initial activating program for activating an initial process to turn on a power source of the apparatus is stored in said rewrite inhibition bank, and when the power source of the apparatus is turned on, a processor accesses said initial activating program and starts an initial process.

11. An apparatus according to claim 10, wherein said processor checks the flag information in all of the banks in said memory at the time of said initial process, and when said first bank is valid, said processor writes back the data in said first bank into the bank of the backup source and, thereafter, executes a next process.

12. An apparatus according to claim 1, wherein an initial activating program for activating an initial process at the time of turn-on of a power source of the apparatus has been stored in a certain specified bank in said memory, said processor checks the flag information in all of the banks in said memory at the time of said initial process, and when the bank in which said initial activating program has been stored is invalid and said first bank is valid, an access address to said initial activating program by said processor is converted to an address of said first bank, the initial activating program in said first bank is loaded into a work memory, and after that, the initial process is started.

13. An apparatus according to claim 1, wherein said rewrite processing means inhibits accesses other than the rewriting to said memory during the rewriting operation.

14. An apparatus according to claim 13, wherein said rewrite processing means copies a program of the bank which is activated by another access during the rewriting operation into a work memory and inhibits an access to said memory during the rewriting operation.

15. An apparatus according to claim 1, wherein when a plurality of processors operate while sharing said memory and a work memory, a specified processor to execute a rewriting process is set to a main processor, and when a rewriting instruction is received, said main processor inhibits an access to said memory by the other processor and, after that, starts the rewriting process.

16. An apparatus according to claim 15, wherein when the rewriting instruction is received, said main processor

copies a rewriting program in said memory to realize said rewrite processing means into said work memory, and

after completion of the copy, instructs the other processor so as to jump to the rewriting program in said work memory when accessing to said memory,

the other processor which received said instruction jumps to the rewriting program in said work memory and, after that, notifies the execution of the jump to said main processor and shifts to an infinite loop, and

after confirming that all of the other processors jumped to the rewriting program in said work memory, said main processor itself also jumps to said rewriting program and starts the rewriting process of said memory.

17. An apparatus according to claim 15, wherein when the rewriting instruction is received, said main processor copies a rewriting program in said memory to realize said rewrite processing means into said work memory and halts all of the other processors after that, and after completion of the halting, said main processor jumps to the rewriting program in said work memory and starts the rewriting process of said memory.

18. An apparatus according to claim 1, wherein said rewrite processing means checks a rewriting format added to new data for rewriting prepared in a work memory and, in the case where said rewriting format instructs a rewriting of all data in the second bank, said rewrite processing means starts the rewriting process of said memory on a bank unit basis by using said new data as it is, and

in the case where said rewriting format instructs the rewriting of partial data in the second bank, said rewrite processing means copies all of the data in the second bank into said work memory and rewrites said partial data by said new data and, after that, starts the rewriting process of said memory by using the data after completion of the rewriting operation.

19. An apparatus according to claim 18, wherein in the case where said rewriting format instructs the rewriting of partial data of the second bank and also indicates the presence of old data, said rewrite processing means copies all of the data of the second bank into said work memory, checks the old data, starts the rewriting process of said memory by using the data a part of which was rewritten by new data when said old data is normal, and finishes the rewriting process as an abnormality when said old data is abnormal.

20. An apparatus according to claim 1, wherein said memory holds a parity of the data of each bank into the same bank, thereby enabling the data to be rewritten for only the inside of said bank as a target.