[rescue] Wide disk on Narrow bus, reprise

[Curious George]

Hi, Mark,

--- Mark <md.benson at gmail.com> wrote:

> I have quite a bit of experience of using wide discs
> on narrow busses,  

Great!  :>

> mostly in Macs and Amigas. In my experience, you
> need to get hold of 2  
> things - a terminator for the end of the 50 pin
> ribbon (and a ribbon  

Why does the ribbon need an extra terminator?

> with a spare stop at the end) and a 68-50 pin
> adapter that terminates  
> the upper byte at the back of the drive. In theory
> wide drives should  
> drop to narrow automatically once the upper btye is
> terminated, but I  
> guess Fujitsu had to be awkward ;)
> 
> All my 68-50 adapters have 'ACTIVE UPPER' embossed
> on the casing and  
> all came from the same place that I asked
> specifically for that type.  
> I've used many Seagate (Cheetah & Barracuda) and IBM
> Ultrastar drives  

I think these were cheetah's.  I nkow I have a lot
of Fujitsu (and Compaq rebadged Fujitsu's) but those
are SCA.

> this way in 50-pin machines relatively successfully.
> Quantum drives  
> are touch and go, some of mine work on 50-pin legacy
> machines and some  
> don't but the ones that don't have Dell or Compaq
> part numbers and  
> drive IDs on them. To be frank I've never tried
> Fujitsu drives, I  
> don't own any and nor do I want to (friends have had
> bad experiences with them even from new).
> 
> That's my 2p worth.

It's my understanding that the drive should request
wide transfers (negotiation) and, if the host
declines, fall back to narrow.  I.e., I don't see
anything *wrong* with the approach I have taken...

I'll have to dig through the Standard to see how
much of this is "optional" vs. mandated.

Thanks!


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