From: et472@ncf.ca   
      
   On Wed, 28 May 2008, Joe Zwerko wrote:   
      
   > Knut,   
   >   
   > Thanks for your help, I really appreciate it.  I can't reply to your email;   
   > Comcast complains about "online.no" not being a fully-qualified hostname.   
   >   
   > The WD1791 can still be obtained (for a high price) but the other WD parts   
   > are much harder to find.  Specifically, I can't seem to locate anyone   
   > selling a WD2143-01 or WD1691, so I'll probably have to wait until someone   
   > sells a working DD kit on eBay.   
   >   
   Western Digital numbering was all over the place.  So something like the   
   1770 was an early floppy controller that needed lots of external parts,   
   while the 1773 was the ultimate with a built in data separator, but then   
   there's the 179X series didn't include the data separator.  So   
   there's no big pattern as far as I can see.   
      
   I never had a Western Digital databook, but I have an SMC databook that   
   came out relatively late.  Nothing about the 2143 or the 1691.  I looked   
   because I thought the latter might be a 1791 with a slight variation but   
   no, the variations I remember are defined by the last number.   
      
   The number of pins that are on these ICs may give an idea.  A forty pin   
   sounds like a full floppy disk controller, while 8 pins would be more   
   likely to indicate a data separator.   
      
   I just tried the "WD2143-01" with a search engine, and the first page   
   is one about the LNW-80.  No datasheet, but it says it's a "Four Phase   
   Clock Generator".  It says the "WD1691" is "floppy support logic".   
      
   The other hit is a patent, do the search and see.   
      
   Do a search on the "WD1691" and skip over the hits about datasheets.   
   You'll find another LNW-80 page that is descriptive.   
      
      Michael   
      
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