Re: Daisychaining 5.25 " Drives

["mdj" <mdj.mdj@gmail.com>]

Michael J. Mahon wrote:

> IIRC, the 5.25" drives must be at the end of the daisy-chain, so
> the last smartport device must synthesize drive 1 and 2 select lines
> for the downstream devices, and must also pass on (or regenerate)
> all the standard 5.25" vrive signals.

That sounds reasonable, yes.

> I expect that there is an signal line that a drive supplies to the
> interface that says whether it is a smartport device or not, and
> the interface responds accordingly, even through intermediate
> smartport devices.

Hmm, I'm not sure how, since the //c Smartport, Liron card and 5.25"
controller card are essentially identical, and contain signalling
that's only relevant to 5.25" drives.

I seem to recall there was a modification made to analog controller
board in the Platinum 5.25" drives that allowed them to respond to a ID
request while still essentially being 'dumb' devices - the Apple 3.5"
and Superdrive have the same feature, I think.

Surely the electrical characteristics of SmartPort are documented
somewhere? Perhaps in one of the IIGS reference manuals I don't have.

Matt