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A method to execute complete test of DRAM Disclosure Number: IPCOM000140521D
Publication Date: 2006-Sep-12
Document File: 2 page(s) / 11K

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The Prior Art Database


Improve a method of DRAM test at manufacturing test process of hard disk drive. The ECC( Error Correction Code ) function is utilized. It can detect DRAM defect by write/read operation. But, it covers limited DRAM area, because it is applied sector buffer area only. The idea is to execute DRAM test by write/read operation with no limited DRAM area.

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A method to execute complete test of DRAM

   It takes long time for manufacturing test of hard disk drive, almost of it searches defects on the disk by write/read operation.

And the sector buffer is used at that time.

The ECC function applied for sector buffer area ( write/read data area ), DRAM defect is detected by ECC function on sector buffer area.

But, DRAM has another area as working area, there is no capability to detect DRAM defects in this area by ECC function.

Because, this area never used for write/read operation as sector buffer.

It is separated by MSB ( Most Significant Bit ) as below.

Current Address Line Logic:

Address line (MSB: Most Significant Bit) ------------------------> DRAM Address line

Add new function to have a capability to invert address MSB for swapping sector buffer area and working area as below.

New Address Line Logic:


| |

Address line (MSB: Most Significant Bit) ----------| XOR |-----> DRAM Address line
(MSB) | |

Address inversion ---------------------------------| | +-------+

It could be supported by HDC ( Hard Disk Controller ) register setting or MPU ( Micro Processing Unit ) IN/OUT.

DRAM memory map is as blow.

>>>>> DRAM total area <<<<< +-----------------+-------------------------------------------------------+
|#################| | | Working area | Sector buffer Area | +-----------------+-------------------------------------------------------+

1.Operation mode (Address inversion = 0) ( Same as now ) +-----------------+------------------+------------------------------------+
|#################| . | | | . | +-----------------+------------------+------------------------------------+
<----------------------------------->|<---------------------------------->| Address line MSB = 0 Address line MSB...