The Apple DuoDisk cable is DB25 to DB19.  I used the following to make my
own cable:  
On Thu, Aug 14, 2014 at 12:49 PM, Chris Osborn <fozztexx at fozztexx.com>
wrote:
 On Aug 14, 2014, at 8:58 AM, Alexandre Souza <alexandre.tabajara at gmail.com>
 wrote:
  Cindy, do you have a duodisk cable? It is a db19
in each end 
 Are you sure about that? My duodisk has a DB25 on it, not a DB19. The DB19
 for daisy chaining is only on the single 5.25" drives and on the Apple II.
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