[TUHS] Bootstrapping UNIX - how was it done

[Angelo Papenhoff via TUHS]

The booting procedure is described in the manual in bproc(7) in v1 and
v2, bproc(8) afterwards. A fun read :)

http://squoze.net/UNIX/v1man/man7/bproc
http://squoze.net/UNIX/v2man/man7/bproc
http://squoze.net/UNIX/v3man/man8/bproc
http://squoze.net/UNIX/v4man/man8/bproc
http://squoze.net/UNIX/v5man/man8/bproc
http://squoze.net/UNIX/v6man/man8/bproc

On 23/03/26, Peter Weinberger (温博格) via TUHS wrote:
> As I remember, the 11/70 was booted just as John describes. One keyed
> in a boot loader at the console.
> 
> On Mon, Mar 23, 2026 at 3:11 AM John P. Linderman via TUHS
> <tuhs at tuhs.org> wrote:
> >
> > >
> > > >How was UNIX bootstrapped in the early days?
> > >
> > > When I started at the Labs in 1973, what eventually morphed into the
> > Programmer's Workbench UNIX ran a PDP45 in Piscataway, NJ. UNIX was
> > sufficiently flakey at that time that they liked to reboot the system each
> > day to clean up corruption in the file system. Someone noticed that I
> > arrived before 6 am every morning, when a reboot would go unnoticed by most
> > people. So I was taught how to halt the system, set a bunch of keys on the
> > front of the 45, and hit start. I'm guessing that the keys simply directed
> > the 45 to read a boot block from some device, and execute the instructions
> > in that block, where the real software bootstrapping began. I'm sure others
> > in this group can supply the correct details. I was not then, and still am
> > not now, a hardware person, but I remain an early riser. -- jpl