The invention provides a method of managing data updates in DOS-based data storage device having an OTP memory die that includes a code region having a first memory capacity and a code region access resolution and a data region having a second memory capacity and a data region access resolution. The second memory capacity is larger than the first memory capacity and the code region access resolution is finer than the data region access resolution. The method includes chronologically writing a log entry in the code region indicating the change in FAT and root directory for each change in user data written in the data region.