Intel Corporation

Timothy Wade Goodell

Mickey L Fandrich

Richard J Durante

Geoffrey A Gould

Thomas C Price

Salim B Fedel

Scott M Doyle

A method of queuing erase commands for a nonvolatile memory utilizes placeholder commands to prevent the depth of an operation queue from limiting the number of block erase commands that can be queued at one time. The method includes the step of storing a first erase command in the operation queue. The first erase command is designated as a placeholder erase command if no placeholder command is stored in the operation queue. Each of the first and placeholder erase commands designates at least one block of the nonvolatile memory to be erased. Each block has a corresponding status indicator. If a placeholder erase command is already stored in the operation queue, then 1) the corresponding status indicator for the block designated by the first erase command is set to indicate that the first erase command is an absorbed erase command, and 2) the first erase command is removed from the operation queue. If a program command designating the same block as any of the placeholder and absorbed erase commands is stored in the operation queue, then 1) an erase operation for the same block is performed; 2) the corresponding status indicator for the same block is cleared; and 3) the program command is executed. If the program command does not designate the same block as any of the placeholder and absorbed erase commands, then 1) the program command is executed; and 2) the program command is removed from the operation queue.

Methods for queuing and absorbing erase commands in a nonvolatile memory

A method of prioritizing program and erase commands received in an operation queue for a memory includes the step of storing a placeholder erase command in the operation queue. Subsequent erase commands are absorbed by 1) storing the subsequent erase command in the operation queue; 2) setting a corresponding status indicator for the block designated by the subsequent erase command; and 3) removing the subsequent erase command from the operation queue, wherein the subsequent erase command becomes an absorbed erase command. If a program command that designates a same block as any one of the placeholder and absorbed erase commands is stored in the operation queue, then 1) the same block is erased; 2) the status indicator for the same block is cleared, if the same block is associated with the absorbed command; 3) the program command is executed; and 4) the program command is removed from the operation queue. If the program command does not designate a same block as any one of the placeholder and absorbed erase commands, then 1) the program command is executed; and 2) the program command is removed from the operation queue. In either case, the method then returns to continue absorbing subsequently received erase commands. This allows more erase commands to be queued for execution than what the depth of the operation queue otherwise permits.

Methods for prioritizing erase and program commands in a nonvolatile

A method of prioritizing program commands relative to erase commands in an operation queue for a memory includes the step of initiating an erase of a first block for a first erase command in the operation queue. The memory has a status indicator for each block. The status indicator indicates whether an erase command for its corresponding block has been received and removed from the operation queue but not yet executed (e.g., an absorbed erase command). An interrupt window is executed during the erasure of the first block to determine if the operation queue has received a second command for a second block. If the second command is a program command, then one of three steps is executed. If the first and second blocks are the same, then execution of the program command is deferred until after the erasure of the first block is complete. If the first and second blocks are not the same then the program command is either executed or deferred in accordance with the status indicator for the second block. If the status indicator for the second block indicates that it has been absorbed (e.g., it is set), then execution of the program command will be deferred until after the erasure of the first block is complete. Otherwise, if the status indicator for the second block indicates that it has not been absorbed (e.g. not set), then the erasure of the first block will be interrupted to execute the program command.

Method of prioritizing subsequently received program and erase commands

A method and device for selectively enabling and disabling write access to flash blocks in a flash memory device. A lock command locks and unlocks a flash block in a flash array containing a plurality of flash blocks. A block data row decoder selects a block data area of the flash block, and a block status row decoder selects a block status area of the flash block. A lock bit in the block status area is programmed to a first logic state if the lock command specifies a lock flash block operation, or to a second logic state if the lock command specifies a release flash block operation. If a write protect input, read from the write protect pin of the flash memory device, indicates that a write lock is enabled and if a block enabled status bit in a block status register corresponding to the block indicates that the block has the write lock, then the lock bit is read and stored into the block enabled status bit in the block status register corresponding to the block. The write protect input is read again from the write protect pin and if the write protect input indicates that the write lock is enabled, and if the block enabled status bit in the block status register corresponding to the block, as updated, indicates that the block has the write lock, then an error is signaled.

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Elk Grove, CA, United States of America

Timothy Wade Goodell