The format of a 2.11BSD boot tape is:

File Block Content
# Size
---- ----- -------
0 512 bootblock,bootblock,boot
1 1024 disklabel
2 1024 mkfs
3 1024 restor
4 1024 icheck
5 10240 root.dump
6 10240 tape1.tar1
7 10240 tape1.tar2
8 10240 tape2.tar1

The complete kit will fit on a TK50 (barely) or a 6250BPI 9-track.
Obviously a DAT (4mm) or 8mm tape will have no problem.

For TK25 or 1600BPI 9-track files 0 thru 7 go on volume 1 and
file 8 goes on a second volume by itself (it barely fits, be sure
you don't have a tape that's short of being a 2400' reel).

You can either use the 'maketape' program to write files 0 thru 4
on the tape or use a series of 'dd' commands.

To use 'maketape':

cc -o maketape maketape.c
./maketape /dev/nrmt0 maketape.data
dd if=root.dump of=/dev/nrmt0 bs=10240c
dd if=tape1.tar1 of=/dev/nrmt0 bs=10240c
dd if=tape1.tar2 of=/dev/nrmt0 bs=10240c
dd if=tape2.tar of=/dev/rmt0 bs=10240c

Using only 'dd':

cat mtboot mtboot boot | dd of=/dev/nrmt0 obs=512 conv=osync
foreach i (disklabel mkfs restor icheck)
dd if=${i} of=/dev/nrmt0 obs=1024 conv=osync
end
dd if=root.dump of=/dev/nrmt0 bs=10240c
dd if=tape1.tar1 of=/dev/nrmt0 bs=10240c
dd if=tape1.tar2 of=/dev/nrmt0 bs=10240c
dd if=tape2.tar of=/dev/rmt0 bs=10240c

The setup and installation documents are in the files 'setup.ascii'
and 'setup.ps'. The first file is plain ASCII text while the second
is postscript suitable for sending to a laser printer or ghostview.