On Mon, 24 Jul 2000, Henry B. Hotz wrote:

> This is hardware and therefore a touch off-topic, but anyway. . .
> 
> This beast appears to have no SCSI termination power.  Therefore you 
> need something like a Seagate drive on the internal end in order to 
> power the terminators, if any, on the motherboard.  Is there a jumper 
> option on the motherboard to control this?

According to the developer note, Centris_660AV_Quadra_840AV.pdf
(Apple's Web site) there are no terminators on the mother board on the
internal side (but there is term power). There is "automatic"
termination on the external side if no external drive is attached, but
you must be terminated on the last internal drive.

> I'm extrapolating a bit from the configuration of the drive that the 
> machine came with and the fact that I can't substitute a Quantum from 
> another machine and have it work.  Any other explanation for why I 
> can't move the primary drive to the end of the chain and take that 
> Seagate out?  The Seagate was configured to supply termination power 
> both to the bus and to the on-board terminators.

You think the Quantum doesn't supply term power? Odd. The only reason
Seagate has the jumper, I think, is that the rule is to have no more
than three devices supplying term power, even though it probably
shouldn't matter if they do. (Ground always trumps V+, yes?)

Any chance you have the terminators on the Quantum backwards? They
usually have a little mark that lines up with pin 1 on the drive. If
not that, they used to make active terminators for internal drives.
It's a 2" x 4" circuit board with a 50 pin male connector, assuming
you can still find one.



Frederick