STARTUP AND SHUTDOWN
--------------------

You can login as ken, doug or dmr ('Dennis MacAlistair Ritchie'), using
the same password as the login name. There is no way to safely shut down
V0, just power down the machine and hope for the best:

  Ctrl-E        # stop the SIM emulator
  sim> quit     # quit the SIM emulator

Log out with: Ctrl-D.

ISSUES
------

The very first system Ken Thompson, and others, wrote on a PDP-7 in
1969-1970 was more a proof of concept then a working system. It was after
moving UNIX to the PDP-11/20 in 1971 that the real work began (and even
then, it took a couple of years before "UNIX" started to look like the
thing we know and love today). In addition to this, "V0" is only a
snapshot of the meager sources that has survived or been painstakingly
reconstruced, it is incomplete.

The system does not have mkdir or chdir (i.e. 'cd'), so you'll need to 
organize your files in a flat namespace.

You can only connect one extra telnet session into this system.

PS: Persistent storage is not very reliable in this system.

USER MANAGEMENT
---------------

The kernel and password files are not directly accessible from the live
V0 system. If you really want to add a new user, you can git clone the
https://github.com/DoctorWkt/pdp7-unix project, edit build/fs/password
and rebuild - Good luck ;)

GENERAL USAGE
-------------

As we have already alluded to, there is very little you can actually do
on this system. If you log in as dmr, you can play with B code (the C
precursor). E.g:

@ ls
..
as.s
b.b
b_readme
bi.s
bl.s
dd
hello.b
op.s
system
@ b hello.b hello.s
@ as op.s bl.s hello.s bi.s
@ a.out
Hello, World!
@

You'll find about 50 programs in the system directory, some useful
examples are cat, cp, date, ed, ls, mv, od, rm and roff. Note that ed
doesn't parse any command line arguments, so start it up, write your
file, and then save it with "w myfile". (or conversely, start ed, read in
the file with "r myfile", and save with "w").

Writing manpages and bashing your head against B and PDP-7 assembly, is
about the only things you can do on this system. If you make a spelling
mistake, use # to delete the previous character or @ to delete the whole
line. When you get bored enough V0 provides two games; ttt (tic-tac-toe)
and moo (mastermind). ttt is played in a 3D board of 4x4x4 grids, you
specify your moves with 3 digits (the x, y and z coordinates). Moo is a
mastermind game where you guess 4 digits. You'll get a "bull" if one
number is correct and in the correct place, and a "cow" if a number is
correct but in the wrong place. 

Some tips:

  fsck, ps:  nope.

  which: ls system

  - or more elaborately:

    ls system >temp
    ed
    r temp
    /cmd/p    # "?" = it doesn't exist
    q
    rm temp

  printing system/* in compacted form:

    ls system >temp
    ed
    r temp
    0a
    .PP
    .
    w    # Not "wq" - that writes to file "q"!
    q
    roff temp >junk
    ed
    r junk
    6,10p
    q
    rm junk temp

  paginating through a long document:

    ed
    r maksys.s
    1,22p
    22,44p
    44,$p
    q

  (yes, it really is *that* difficult!)

Good luck, you're gonna need it :)
