From: muratlanne@gmail.com   
      
   "Bob La Londe"  wrote in message news:104n187$ga5q$1@dont-email.me...   
      
   A 1TB micro SD card weighs about 0.5 grams and costs about $100.  That   
   is $2834 dollars per ounce.   
      
   ------------------------------------   
      
   The raw material is sand, the manufacturing cost is all processing, testing   
   and handling. Writing one test pattern to all 10^12 memory locations takes   
   ~2 hours at 140 MB/s, checking it nearly an hour and a half. The tests I run   
   on new multi Terabyte spinning hard drives run for nearly a day.   
      
   I used to build the machines that performed production line IC testing.   
   Typical memory data patterns (vectors) are 55 (01010101) and AA (10101010)   
   to check for adjacent bits shorted together or dead ones. Others are   
   specific to what's likely to go wrong and were customers' secrets.   
      
   To some extent spare cells can be substituted for bad locations (CHKDSK) but   
   they are a warning of future problems. The S.M.A.R.T. data for a drive gives   
   the count of reallocated spares and other issues. I save it when the drive   
   is new and occasionally check if the repairable error count has increased.   
      
   I learned enough at that job to design, build and program my own computer.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)