Re: CFFA Status?

[bieling@terra.es (Jorge Chamorro Bieling)]

ziggy <ziggy@fakedaddress.com> wrote:

> > 
> > There's still a potential issue of termination power...
> > Does the RAMFast supply term power unconditionally?
> > 
> > And did you have a disk in the Zip and powered up when the
> > Apple was powered up?  (Obvious, I know, but had to ask.  ;-)
> > 
> > -michael
> > 
> > Music synthesis for 8-bit Apple II's!
> > Home page:  http://members.aol.com/MJMahon/
> > 
> > "The wastebasket is our most important design
> > tool--and it is seriously underused."
> 
> Yup.. had a disk in there on power-up. 
> 
> Powered up the zip first. Then the IIGS.
> 
> Tried it with the terminator switch both on, and off.

What happens with Zips is that they don't supply the (required)
termination power (that's the termpower pin in the scsi connector), so
even when you think that the scsi chain is properly terminated it may
not be so if the scsi card is not supplying it to the DB25's pin 25 and
the zip is the only device in the scsi chain.

You can check this easily with a multimeter.

I there are not +5v in this pin, you can daisychain the zip to yet
another scsi device that you know that supplies termpower. Most hard
disks do it. Be sure to check that the scsi ids are different for each
device in the chain.

But then, there will be 3 devices in the chain:

-if the scsi controller card does have a terminator built-in, only the
last device in the chain needs to be terminated.

-if the scsi card does not have a built in terminator, both should have
a terminator either enabled (the zip terminator switch in the on
position) or plugged (if the hd has an external terminator to plug in).

-Although, if the scsi chain is short enough, it may work well with only
only one terninator.

But remember -as this may be the problem- that the terminator does
nothing if there's no termination power (+5v) in pin 25.

Be sure to also check the scsi id settings.

Good luck.
-- 
Jorge Chamorro Bieling