ID jumper obsolete

Gerry Houlder Gerry_Houlder at notes.seagate.com
Wed Jan 24 10:04:19 PST 1996


* From the SCSI Reflector, posted by:
* <Gerry Houlder  <Gerry_Houlder at notes.seagate.com>>
The gist of Gary Watson's message was:

>Forgive me if I missed something, but didn't everybody
>agree that we still needed a way to use ordinary 
>jumper shunts to set ID to support legacy applications?
>Obviously this mandates a header somewhere else on
>the drive.  Is it the thinking that SCAM makes this
>no longer a requirement?

I believe the pin assignments for the pins opposite the ID pins are all outputs
(like LED output). This was done on purpose so that the drive will ground these
pins just before it reads the ID pins, then it will return those other pins to 
their
official purpose. This means that reading the ID is restricted to certain times
(like only at power on and during SCSI bus reset) but most products were
restricted to these times anyway.

Using jumpers means you don't get the output functions opposite the ID pins,
but the ID pins still work with the jumpers. This should be specified in the SFF
document, so it should apply to anyone's drive and not just Seagate.




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