Thank you very much for the link : https://www.tuhs.org/

 The Unix Heritage Society's aims include:

    The preservation and maintenance of historical and non-mainstream UNIX systems;
    The further development of existing UNIX systems; and
    The continual fostering of the Unix community spirit.


The Unix Tree
https://minnie.tuhs.org/cgi-bin/utree.pl
Welcome to the Unix Tree. 
Here you can browse the source code and manuals of various old versions of Unix.

https://minnie.tuhs.org/cgi-bin/utree.pl?file=V1/u0.s

. = orig+400
/ copy in transfer vectors

	mov    $ecore,sp / put pointer to ecore in the stack pointer
	jsr    r0,copyz; 0; 14 / clear locations 0 to 14 in core
	mov    $4,r0
	clr    r1
	mov    r0,(r1)+ / put value of 4 into location 0
	mov    r0,(r1)+ / put value of 4 into location 2
	mov    $unkni,(r1)+ / put value of unkni into location 4;
                            / time out, bus error
	clr    (r1)+ / put value of 0 into location 6
	mov    $fpsym,(r1)+ / put value of fpsym into location 10
	clr    (r1)+ / put value of 0 into location 12
/ clear core
	.if cold / ignored if cold = 0
	halt / halt before initializing rf file system; user has
             / last chance to reconsider
	.endif

	jsr    r0,copyz; systm; ecore / clear locations systm to ecore
	mov    $s.chrgt+2,clockp / intialize clockp
/ allocate tty buffers; see H.0 for description
	mov    $buffer,r0
	mov    $tty+6,r1
1:
	mov    r0,(r1)
	add    $140.,r0 / tty buffers are 140. bytes long
	add    $8,r1
	cmp    r1,$tty+[ntty*8] / has a buffer been assigned for each tty
	blo    1b
	
	*****************************************************************
	https://www.bell-labs.com/usr/dmr/www/hist.html
	
	The Evolution of the Unix Time-sharing System*

    Dennis M. Ritchie
    Bell Laboratories, Murray Hill, NJ, 07974 

    ABSTRACT
    This paper presents a brief history of the early development of the 
    Unix operating system. It concentrates on the evolution of the file 
    system, the process-control mechanism, and the idea of pipelined 
    commands. Some attention is paid to social conditions during the 
    development of the system. 
	
...