Date   : Mon, 14 Oct 1985 14:06:16 edt
From   : Alan Gunderson <asg0%gte-labs.csnet@CSNET-RELAY.ARPA>
Subject: SB180 & Tandon half-height drives

You can get one Tandon half-height drive to work with a SB180 system
by jumpering it so that the drive is selected all the time.  It should
also be jumpered so that the 'Motor On' function is NOT controlled by
the drive selection, i.e., the seperate 'Motor On' signal line is
used.  Having the drive selected all the time precludes the use of
multiple drives.  There appears to be a strange timing incompatability
between the disk controller on the SB180 and the Tandon drives.  I
think I may have to peel the drive select lines coming out of the disk
controller off and run them into some special circuitry and then into
the Tandon drives to be able to use multiple drives.  For now, I at
least can boot ZRDOS and make back ups.  Be informed that the Tandon
drives don't support the READY line.  You must jumper the JP6
selection on the SB180.  I installed a switch on this jumper, so that
I can get to the SB180 monitor.  When JP6 is wired permanently, the
monitor thinks the drive is always ready, and thus tries to autoboot.
You can fix this be reburning a new monitor PROM, but I haven't gotten
around to this yet.


====Alan Gunderson
uucp:  ...!seismo!harvard!bunny!asg0
csnet: asg0%gte-labs.csnet@csnet-relay.arpa