There are 3 machine language assists here, m40.s, mch.c
and smch.c. The 'C' versions are actually assembler, and only
use the C pre-processor for ifdefs and includes.
The distribution UNIX versions are made using m40.s but this
is unkikely to be best for your machine, change m.h and the makefile.

**** m40.s ****
This is the original Bell one, which they have only tried on
an 11/23. It does run on 11/40's correctly, and also on the
11/34 and 11/60, but see smch.c below for these machines.

**** mch.c ****
This one is for 11/44,45,70

**** smch.c ****
This one is for 11/23,34,40,60.
It correctly backs up from segmentation faults due to
a growing stack for 11/34 and 11/60 processors. This is also
the one to use if you intend to do the `XBUF' mod.

What to do.
Look at the `m.h' file. This contains all the `defines' to
tailor the system to the hardware, plus some extras.
It is included in `../h/param.h', `smch.c', and `mch.c'.
The `makefile' needs to be tailored with the name of the
machine support to be used, and whether or not separate
I/D is available.
You should `make tests' after you have installed the new
system and it is running, to ensure it backs up correctly.

A system is made by `make ???', where '???' represents 'rk'
or 'rl1' or 'rl2'.
It is advised that you 'link' conf to the configuration file
best suited to you, thereafter 'make unix' will suffice.


NOTES:
1)   The code in some files has been  re-arranged  slightly,
     to  reduce  the  number  of  `ifdefs'  required, and to
     remove unnecessary tests on `cputype', as the  `ifdefs'
     do it all:

             machdep.c - comment out test on cputype (70)
             trap.c - make sure that r3 is passed to `backup'
             trap.c - comment out test on cputype (70)
             ureg.c - comment out test on cputype (40)


2)   In the file  /usr/sys/h/param.h,  CMAPSIZ  and  SMAPSIZ
     should  both  be defined as (NPROC/2) otherwise trouble
     will occur with very large memories.
