Title: +038=360.000-OU045T_02-PCD2.m4160 PLS SBC - File system Manual.pdf
Unlike to information stored on e.g. RAM (Random Access Memory), it is not possible modifying information just by addressing and changing the value of the according bits on flash memory. Before a part of flash memory can be re-written after e.g. the dele- tion of data, the according part needs to be erased. By erasing memory, all bits of this part are to be set to 1.If a file is deleted on a flash device, the according area on the device is marked as “freed” but not immediately erased (because the smallest area that can be erased is a sector and this sector can contain many files and not only the one to be deleted). As result, it is not immediately possible re-using the memory that has been occupied by the deleted file. The memory first needs to be compressed (→ erasing memory which is marked as “freed”).2.2.3Compressingaflashdevice