What you are looking at is SDI (not to be confused with ESDI). Originally, it was designed to allow
extreme distances between the disks and the controllers (up to 50', if memory serves). Subsequent
designs were modifed to make it a pain in the rear. The one thing you must always remember about SDI
- ALWAYS HAVE AN ODD NUMBER OF CABLES. They won't work if you don't. They're actually four coax
cables in one sheath, and swap at each connection. Generally, there will be a cable from the drive
to a block on the back of the cabinet, then the large black cables to go from box to box, then the
red cables that connect the block to the controller. I don't know if there is a FAQ specifically
about it, but there is some limitted info on the NetBSD hardware library. And yes, the UDA50 is the
interface. I don't know about the Unibus version, but the Q-bus version (KDA50) is a dual-board set.
Each controller can connect to four devices. Generally, most devices will have an A and B channel,
which allows you to put the drive on two controllers for fault tolerance.
If you need more cables or connection blocks, let me know. I just threw out about 10 dead SDI drives
and have plenty of leftover cables.
--
J. Buck Caldwell
Engineer - Technical Support - Webmaster
Polygon, Inc. email:buck_c_at_polygon.com phone: (314) 432-4142
PO Box 8470 http://www.polygon.com/ fax: (314) 997-9696
St. Louis, MO 63132 ftp://ftp.polygon.com/ bbs: (314) 997-9682
Received on Tue Jul 07 1998 - 15:51:29 BST