Example session on a System III.
I was able to compile several other shells (named "sh-..." below) from their original source code on this system.
User input in bold face.

    $ pdp11 run.conf

    #0=unix

    UNIX/3.0.1: unixhpht
    real mem = 262144 bytes
    avail mem = 195136 bytes
    unix
    single-user
    # mount /dev/rp1 /usr
    WARNING!! - mounting: <> as </usr>
    # init 2
    # process accounting started
    errdemon started
    cron started
    multi-user
    type ctrl-d
    ^D
    login: root
    UNIX Release 3.0
    # uname -a
    unix unix 3.0.1 hpht
    # ps -edalf
      F S    UID   PID  PPID  C PRI NI    ADDR SZ    WCHAN   STIME TTY TIME COMD
      3 S   root     0     0 80   0 20    1547  2    30452 14:26:53  ?  0:31 swapper
      1 S   root     1     0  0  30 20    2027 23    25334 14:26:53  ?  0:00 INIT 2
      1 S   root    40     1  0  30 20    2317 44    25372 14:27:10 co  0:00 -sh
      1 R   root    46    40  0  50 20    5215 52          14:27:24 co  0:00 ps -edalf
      1 S   root    30     1  0  26 20    4151 16     3510 14:27:07  ?  0:00 /usr/lib/errdemon
      1 S   root    36     1  0  40 20    4673 27   140000 14:27:07  ?  0:00 /etc/cron
    # stty -a
    speed 300 baud; line = 0; intr = DEL; quit = ^|; erase = #; kill = @; eof = ^d; eol = ^`
    parenb -parodd cs7 -cstopb -hupcl cread -clocal
    -ignbrk brkint ignpar -parmrk -inpck istrip -inlcr -igncr icrnl -iuclc
    ixon ixany -ixoff
    isig icanon -xcase echo -echoe echok -echonl -noflsh
    opost -olcuc onlcr -ocrnl -onocr -onlret -ofill -ofdel tab3
    # ls -l */sh
    -rwxrwxrwx   1 root     0          23224 Jan  3 23:03 sh-svr1/sh
    -rwxrwxrwx   1 root     0          33018 Jan  3 23:06 sh-svr2/sh
    -rwxrwxrwx   1 root     0          43420 Jan  3 23:11 sh-v8/sh
    -rwxrwxrwx   1 root     0          21924 Jan  3 22:36 sh/sh
    # cd sh-v8; ./sh
    # f() { echo function; }
    # export f
    # ./sh
    # whatis f
    f(){
    echo function
    }
    # cd /usr/src/cmd/sh-v  # spell checker
    /usr/src/cmd/sh-v8
    # pwd
    /usr/src/cmd/sh-v8
    # shutdown

    SHUTDOWN PROGRAM

    Mon Jan  5 14:35:53 EST 1970

    Broadcast Message from root
    SYSTEM BEING BROUGHT DOWN NOW ! ! !
    [...snipped]

<http://www.in-ulm.de/~mascheck/various/ancient/sys3.html>