first step getting VAX 6000-400 booted ... - test-drb@ccmp.vtda.org

24 Oct 2001

	Peter Wallace wrote:

...
 Something I remember on RA81s is that you have to go
from
controller --> cable --> bulkhead connector --> cable  --> disk

if you go directly from controller to disk, you end up with pins swapped
...
 and things dont work (but nothing hurt) 
	I think the rule is you have an *odd* number of
	connecting cables - since each cable swaps.

	So in a MicroVAX 3600 you can go directly from
	KDA50 controller to RA7x internal drive. Or you
	can go from KDA50 to bulkhead, bulkhead to
	bulkhead on next cab (e.g. storage array) and
	from there a third cable goes internally from
	bulkhead to final drive.

	In the case of a 6000 typically you go from
	KDB50 (or KDM70) to bulkhead on 6000 chassis.
	Then 6000 chassis to Storage Array chassis.
	Then internally there is a cable from the
	Storage Array bulkhead to the drive itself.

	I don't know how the wiring was done for
	those later kits that allowed RA9x and/or
	RA7x drives to live in the bottom of
	the VAX 6000 chassis.

	Antonio