Pinout for SED9421

[Chuck Guzis]

On 11/28/2005 at 2:00 PM Allison wrote:

>Often they were used because WD could not supply or was
>not viewed as the desireable item due to lack of second 
>source (at least early on).  Some did it to have a 
>propritory format.

Let's not forget that the 1771 early on was pretty darned expensive, too!
A USRT was almost always cheaper, particularly where software could be
brought to bear to issue timed step pulses, search for index/sector pulses,
etc.  All USRTs AFAIK, can recognize sync characters embedded in an idle
bit stream, which doesn't make them too different from floppy controllers.

Cheers,
Chuck