US 5,524,230 A · External information storage system with a semiconductor memory

Abstract

To provide an external storage system using a semiconductor memory in which the data reading and writing between the host CPU can be processed faster than the conventional magnetic disk, and only a particular sector is not frequently written and erased so that the whole memory is effectively used over a long period of time. An address control scheme was introduced in which flexibility is given to the address relation between the host CPU and the external storage and the physical address of the semiconductor memory is not one-sidedly determined by the logical address possessed by the command of the host CPU. Command processing section 34 always prepares memory blocks and sectors for writing or erasing and copying in preparation for the command processing of the host CPU, and records and holds the correspondence relation between the physical address of the selected memory block 32i or sector and the command of the host CPU in address conversion table 36. The status of memory blocks and sectors is recorded in respective managing tables 35 and 60, and used for control of processings such as writing, erasing and copying in preparation for or in response to the command of the host CPU.

Claims17

Dependent claims

A method of controlling an external storage system comprising a semiconductor memory as an external storage device, the external storage device further comprising a flash memory having a plurality of memory blocks each memory including at least one sector, and a control section, including a block managing unit for performing control over said memory blocks, and for maintaining a record of the number of times each memory block has been erase and the status of each memory block and sector, the external storage system being connected to a host processor through a bus for transferring data and a command, the method comprising the steps of:

selecting, under control of the control section, a memory block for which data is written or erased on the basis of the record of the block managing unit,
converting a logical address included in a command of the host processor to a physical address indicating a corresponding sector in a particular memory block, responding to one of three different commands to perform a process of data writing or reading to the corresponding sector or memory block erasure,
sequentially updating the status changes of each sector and memory block resulting from the processes in the block managing means, and
recording and updating the relationships between the physical addresses and the logical addresses of the memory block and sector on which the processes were performed in the address conversion means.

1 more element

A method for controlling a computer system comprising a host processor, a semiconductor memory used as an external storage device, the external memory further comprising a flash memory having a plurality of memory blocks each including at least one sector, and a control section including a block managing unit for performing control over memory blocks, and for maintaining a record of the number of times each memory block has been erased and the status of each memory block and sector, the method comprising the steps of:

converting, under control of the control section the logical address included in the command of the host processor to a physical address indicating the sector in a particular memory block by an address conversion means,
selecting a memory block for data writing and a memory block to be erased next to acquire the memory block for data writing, respectively, on the basis of the record of block managing means which has sequentially recorded therein the number of times each memory block was erased and the status of each sector and memory block,
writing the data to be written received from the host processor into the memory block for writing,
erasing the selected memory block for erasure, and
executing a process of data writing, reading or erasing to the memory block or sector that has the physical address obtained from an address conversion table in response to the command.

2 more elements

An external storage system connected to a host processor through a host bus for transferring data and at least one command, the storage system comprising:

a semiconductor memory comprising a flash memory having a plurality of memory blocks each including at least one sector,
address conversion means for converting a logical address received from the host processor to a physical address corresponding to a particular sector, and
block managing means for recording the status of each memory block and sector, and a control section which uses the record of the block managing means to control the reading or writing of data to each sector of the semiconductor memory, or the erasing of a memory block, said address conversion being done on the basis of the record.

Dependencies are inferred from the claim text.

External information storage system with a semiconductor memory

Life of this patent

External information storage system with a semiconductor memory

Life of this patent

Abstract

Claims17