Date   : Tue, 01 Oct 1985 10:37:14 edt
From   : Alan Gunderson <asg0%gte-labs.csnet@CSNET-RELAY.ARPA>
Subject: SB180 help

I have purchased a SB180 board and have wired it into a power supply
and installed two Tandon TM-65-2 48 tpi 5-1/4" DSDD drives (80 tracks
per drive, unformatted 500K bytes maximum storage).  These
drives do not support the READY line, so I have installed the JP 6
jumper on the SB180, which makes the disk controller think the disk
drives are always ready.  The ROM monitor on the SB180, when it see's
that the drives are ready, assumes that the user wants to autoboot from
the floppy.  When I try to boot the ZRDOS operating system, I get
the operating system sign-on for version 2.1 of ZRDOS.
According to the manual, this indicates that ZRDOS has
been correctly loaded into memory.  I then get the message

     Read Error on A:

     I have installed a switch as part of my JP 6 jumper, so I can make
the monitor think that the floppies are not ready and thus enter the
command entry state.  From the monitor, I have not been able to format
floppies.  The program disappears for a time and then aborts with a
dump of the disk controller status registers and the head, track, and
sector in which the format dies.  Using the monitor R command, I am
able to read sectors from the operating system diskette.  When I go
beyond sector 9 with the read, I get the same disk controller status
register dump.

     The Tandon drives do not support the Head Load line in the
interface.  This is pin 4 and is listed as a spare for the floppy.
The SB180 manual alludes to the fact that Head Load is not required
but is desirable to extend the life of the diskettes.  Is this line
required?  Is there any way to make the Tandon drives support the
READY line (pin 34)?  The Tandon manual alludes to this line being
optionally enabled, but does not tell how.  There is no jumper
documented.

     Has anyone else tried to interface this type of drive to the
SB180?  If so, please provide any hints or insights.  Any other SB180
ideas??

Thanks in advance.

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