Pinout for SED9421

[Allison]

>
>Subject: Re: Pinout for SED9421
>   From: "Dwight K. Elvey" <dwight.elvey at amd.com>
>   Date: Mon, 28 Nov 2005 10:46:28 -0800 (PST)
>     To: cctalk at classiccmp.org
>
>>From: "Allison" <ajp166 at bellatlantic.net>
>
>>>   From: woodelf <bfranchuk at jetnet.ab.ca>
>---snip---
>>
>>>Did anybody ever use a serial chip and a data separater
>>>rather than a floppy disk controler?
>>
>>Yes, many.  usually its a sync chip.
>>
>>Allison
>
>Hi
> Besides the HeathKit hard sectored controller board,
>used on both the H8 and the H89, Polymorphics also
>used a serial chip to do data. In both of these
>cases, as you state, they used synchronous serial
>chips and not async.

Err, Yes that's what I did say.  Sync chips were the norm
for brewed designs there were not OSI or done with TTL.  

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.


Allison