Method for releasing space in flash EEPROM memory array to allow the storage of compressed data

Claim 2

A process for releasing sectors of a flash EEPROM memory array in which data furnished by a host computer is stored in compressed form so that memory space used for the sectors may be used to store new data, the flash EEPROM memory array including a plurality of individually erasable blocks and storing sectors of data in such blocks with a header providing a logical sector number, an indication of validity of data stored, the process comprising the steps of: storing a list of files and sectors which have been deleted by a host computer in a first table in host memory, storing a value indicating an amount of free space remaining in the flash EEPROM memory array, providing a first signal to the host computer when the value indicating the amount of free space falls below a first predetermined value to indicate that sectors listed in the first table should be released, and providing a second signal when the value indicating the amount of free space falls below a second predetermined value.

Claim 3

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 1 further comprising the step of responding to the second signal by disabling write and erase operations in the flash EEPROM memory array.

Claim 4

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 1 further comprising the step of providing a third signal to the host computer when the value indicating the amount of free space falls below a third predetermined value which is less than the first predetermined value but greater than the second predetermined value to indicate that it is more urgent that sectors listed in the first table be released than when the first signal was given.

Claim 5

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 1 further comprising the step of responding to the first signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table.

Claim 6

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 4 in which the step of responding to the first signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table comprises the steps of writing any valid data remaining in a selected portion of the flash EEPROM memory array having a predetermined number of headers specified as invalid to free space in the flash EEPROM memory array, and erasing the entire selected portion of the flash EEPROM memory array.

Claim 7

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 4 in which the step of responding to the first signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table comprises the steps of: selecting a first sector from the first table, searching a second table for a physical position of a sector selected, seeking a sector specified by a physical position of a sector selected, marking a header of a sector specified by a physical position of a sector selected as invalid, writing a new header for a sector selected in free space in the flash EEPROM memory array without data, updating the second table with a new physical position of a new header for a sector specified by the first designation, and repeating the process from the step of selecting a first designation for a sector from the first table until the predetermined number of sectors listed in the first table have been released.

Claim 8

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 4 in which the predetermined number of sectors listed in the first table is all of the sectors listed in the first table.

Claim 9

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 4 in which the predetermined number of sectors listed in the first table is selected to leave a number of sectors equal to at least one host computer file in the first table.

Claim 10

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 3 further comprising the step of responding to the third signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table.

Claim 11

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 9 in which the step of responding to the third signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table comprises the steps of writing any valid data remaining in a selected portion of the flash EEPROM memory array having a predetermined number of headers specified as invalid to free space in the flash EEPROM memory array, and erasing the entire selected portion of the flash EEPROM memory array.

Claim 12

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 9 in which the step of responding to the third signal by automatically releasing the data allotted to sectors listed in the first table comprises the steps of: selecting a first sector from the first table, searching a second table for a physical position of a sector selected, seeking a sector specified by a physical position of a sector selected, marking a header of a sector specified by a physical position of a sector selected as invalid, writing a new header for a sector selected in free space in the flash EEPROM memory array without data, updating the second table with a new physical position of a new header for a sector specified by the first designation, and repeating the process from the step of selecting a first designation for a sector from the first table until a selected number of sectors listed in the first table have been selected.

Claim 13

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 9 in which the predetermined number of sectors listed in the first table is all of the sectors listed in the first table.

Claim 14

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 9 in which the predetermined number of sectors listed in the first table is selected to leave a number of sectors equal to at least one host computer file in the first table.

Claim 15

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 1 in which the step of storing a list of files and sectors which have been deleted by a host computer in a first table in host memory comprises listing all files and sectors of files indicated to be deleted in a host file allocation table.

Claim 16

A process for releasing sectors of a flash EEPROM memory array in which data furnished by a host computer is stored in compressed form so that memory space used for the sectors may be used to store new data, the flash EEPROM memory array including a plurality of individually erasable blocks and storing sectors of data in such blocks with a header providing a logical sector number, an indication of validity of data stored, the process comprising the steps of: storing a list of files and sectors which have been deleted by a host computer in a first table in host memory, storing a value indicating an amount of free space remaining in the flash EEPROM memory array, providing a first signal to the host computer when the value indicating the amount of free space falls below a first predetermined value to indicate that sectors listed in the first table should be released, responding to the first signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table, providing a second signal to the host computer when the value indicating the amount of free space falls below a second predetermined value to indicate that it is more urgent that sectors listed in the first table be released than when the first signal was given, and responding to the second signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table, providing a third signal when the value indicating the amount of free space falls below a third predetermined value, and responding to the third signal by disabling write and erase operations in the flash EEPROM memory array.

Claim 17

A process for releasing sectors of a flash EEPROM memory array in which data furnished by a host computer is stored in compressed form so that memory space used for the sectors may be used to store new data, the flash EEPROM memory array including a plurality of individually erasable blocks and storing sectors of data in such blocks with a header providing a logical sector number, an indication of validity of data stored, the process comprising the steps of: storing a list of files and sectors which have been deleted by a host computer in a first table in host memory, storing a value indicating an amount of free space remaining in the flash EEPROM memory array, providing a first signal to the host computer when the value indicating the amount of free space falls below a first predetermined value to indicate that sectors listed in the first table should be released, responding to the first signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table, providing a second signal to the host computer when the value indicating the amount of free space falls below a second predetermined value to indicate that it is more urgent that sectors listed in the first table be released than when the first signal was given, and responding to the second signal by automatically releasing the data allotted to a predetermined number of sectors listed in the first table, providing a third signal when the value indicating the amount of free space falls below a third predetermined value, and responding to the third signal by disabling write and erase operations in the flash EEPROM memory array.

Claim 18

A process for releasing sectors of a flash EEPROM memory array as claimed in claim 15 in which the steps of responding to the first and the second signals by automatically releasing the data allotted to a predetermined number of sectors listed in the first table comprises the step of writing all sectors containing valid data to new storage areas from a block storing a plurality of invalid indications, and erasing the block from which the valid data has been written.