Compact Flash 4 series

AP-CFxxxxA5XS-XXXXXX

8

© 2009 Apacer Technology Inc.

Rev. 1.1

5. Flash Management

5.1 Advanced Wear Leveling

The goal of advanced wear leveling algorithms is to evenly spread the program and erase cycles on the

area of programmed and erased multiple times and the area of programmed one and read multiple times

among the available blocks in the flash array.

5.2 Read Recovery Technology

Read Recovery Technology enables reliable storage. When it is detected correctable error during read

command operation, all data of related block is corrected and is moved to other block. Since it continues

to read data after recovery operation, read data is the same as no error data for host system. However,

since data transfer is stopped temporarily, the output time of BSY signal becomes long. In order to

perform Read Command Recovery, it is necessary to set up the threshold for the number of detected

error bit. Read Command Recovery is performed by following commands.



READ DMA



READ MULTIPLE



READ SECTOR(S)



READ VERIFY SECTOR(S)

5.3 Power Failure Recovery

The controller enables to reduce data loss in case of sudden power fail. Once power was failure before

cached data writing back into flash, data in the cache will lost. The next time the power is on, the

controller will check these fragmented data segment, and, if necessary, replace them with old data kept in

flash until programmed successfully.

5.4 S.M.A.R.T. Technology

S.M.A.R.T. is an acronym for Self-Monitoring, Analysis and Reporting Technology and enables to expect

the endurance of flash memory. The S.M.A.R.T. function protects the user from unexpected fault of

product. The S.M.A.R.T function enables to predict the occurrence of near-term degradation or fault

conditions by monitoring and storing critical parameters of flash memory (ex. Number of bad block,

maximum number of erase, etc). The host system is warned of a negative reliability condition which is the

impending risk of data loss by the S.M.A.R.T. function. Then the user can take appropriate action to

minimize the risk.