The only thing I would add is to find yourself a copy of Lion's book: https://en.wikipedia.org/wiki/Lions%27_Commentary_on_UNIX_6th_Edition,_with_Source_Code

You can get a nicely bound version inexpensively from Amazon, although there are PDFs in the wild too.    Like, others I would suggest starting with Sixth Edition if you want to follow John.  The biggest advantage of Seventh besides having more complete toolchains is that the compiler matches K&R Version 1, so you are likely to have fewer issues, you will already be giving up ANSI (as described in K&R2).  I started with Fifth years ago in the early/mid-1970s but quickly got Sixth's so I have little memory of it.  I have played with it on simh since frankly, the differences between 5 and 6 are not going to be huge from a learning standpoint.

On Wed, May 5, 2021 at 2:09 PM Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:
    > From: Saif Resun

    > I want to use the 5th edition UNIX operating system.
    > ...
    > I want to use it using the SimH emulator but there's no guide about
    > how to install it or use it.

As they say,'Google is your friend':

  https://gunkies.org/wiki/Running_Unix_v5_in_SIMH

Also, V6 Unix is very similar to V5 (the main difference, IIRC, is that V6
supports so-called 'Split I/D space' on the PDP-11) so anything for V6 will
mostly apply to V5:

  https://gunkies.org/wiki/Running_UNIX_v6_in_SIMH
  https://gunkies.org/wiki/Installing_UNIX_v6_(PDP-11)_on_SIMH
  https://gunkies.org/wiki/Installing_UNIX_Sixth_Edition_on_Ersatz-11

Have fun!

        Noel