Re: Disk ][ vs Unidisk vs Duodisk vs //c external disk

[nathan@visi.com (Nathan Mates)]

In article <58qo57$r54@nntp.ucs.ubc.ca>,
Tim Shoppa <shoppa@alph02.triumf.ca> wrote:
>Starting 1979 or so the only Apple II disk drives I had ever used
>were Disk ]['s on ]['s, ][+'s, and //e's.  I've recently begun
>running across quite a few drives with 19-pin D connectors:
>Unidisks, Duodisks, and //c external disks.  I've also begun
>entertaining the thought of buying a IIgs.  A few questions:

>1.  Am I correct in assuming that I can just daisy-chain these
>drives onto each other?

   Disk ][s don't really have a port in back to daisy chain off,
so I'd expect that they'd be last on a chain.

>2.  I understand a IIgs can control up to four drives in a
>daisy-chain.

   Yes, but a max of two 3.5" drives (Apple 3.5 and the Unidisks) and
two 5.25" drives.

>  Is this also true for the "Duodisk" controllers
>I've been seeing in //e's?  Or are these limited to a total
>of two drives (a single Duodisk?)

   Two 5.25s.

>3.  What is the wiring of the 19-pin connector?  How is
>drive select handled?  I understand the 20-pin Disk ][ cabling
>quite well, but don't see how it is easily extended to include
>4 drive selects.

   This is referenced from the FAQ. David Empson wrote a rather nice
guide, which is at http://www.visi.com/~nathan/a2/faq/diskiicable.html

Nathan Mates
--
<*> Nathan Mates http://www.visi.com/~nathan/      <*>
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