From wucs!root Sat Mar  8 07:50:44 1986
Date: Fri, 7 Mar 86 14:53:51 est
From: adiron!root (AdironVax)
To: wucs!seismo!keith
Subject: ht.c

Keith - after some studying of  the driver I think we have found the
problem.  The minor device numbers in the /dev/MAKE script are incorrect
and cause the wrong unit to be selected.  The driver seems to be working
fine.  However it is noted in the source that ht.c only supports one
controller.  Therfore it looks like one should never set NHT to be > 1.
The MAKE script does the following:

		WRONG		RIGHT
name	major	minor		minor
mt0	9	0		0		unit0
mt1	9	64		64		unit0
mt2	9	2		1		unit1
mt3	9	66		65		unit1

nmt0	9	128		128		unit0
nmt1	9	192		192		unit0
nmt2	9	130		129		unit1
nmt3	9	194		193		unit1

.. and similar permutations for rmt_ and nrmt_ (major = 17).

The change to MAKE seems simple enough: 
ht*|ut*)
	umask 0 ; unit=`expr $i : '..\(.*\)'`
	case $i in
	ut*) blk=3; chr=12;;
	ht*) blk=9; chr=17;;
	esac
	case $unit in
	0|1|2|3|4|5|6|7)
		name=`expr $unit '*' 2` ; one=`expr $name + 1`
		norew=`expr $unit + 128` ; hidens=`expr $unit + 64`
		norewhidens=`expr $unit + 192`
		mknod mt$name	b $blk $unit
		mknod mt$one	b $blk $hidens
		mknod nmt$name	b $blk $norew
		mknod nmt$one	b $blk $norewhidens
		mknod rmt$name	c $chr $unit
		mknod rmt$one	c $chr $hidens
		mknod nrmt$name	c $chr $norew
		mknod nrmt$one	c $chr $norewhidens
		umask 77
		;;
	*)
		echo bad unit for tape in: $1
		;;
	esac
	;;

It is nice to be sending you a fix for a change - tish
