The cwns command mirrors the cw2dmk command, but is specifically tuned to read NorthStar hard-sectored disks. While cwns is a direct descendant of cw2dmk, it does not offer all the same flexibility of cw2dmk (even though the command help says it does). The actual command lines to use are:
For SSSD:
cwns -d0 -h0 -k2 -s1 -m1 -e1 -t35 -w1 sssd.dmk
For SSDD:
cwns -d0 -h0 -k2 -s1 -m1 -e2 -t35 ssdd.dmk
For DSDD:
cwns -d0 -h0 -k2 -s2 -m1 -e2 -t35 dsdd.dmk