[TUHS] Bootstrapping UNIX - how was it done

[Ron Natalie via TUHS]

Ours indeed had it.  You set 77765000 in the switches, LOAD ADDRESS, 
then START.

I was known to start humming Glen Miller’s Pennsylvania 6-5000 while 
booting up the machine.


------ Original Message ------
>From "John Levine via TUHS" <tuhs at tuhs.org>
To tuhs at tuhs.org
Cc pjw at google.com
Date 3/23/2026 12:20:25 PM
Subject [TUHS] Re: Bootstrapping UNIX - how was it done

>It appears that Peter Weinberger (温�  � �) via TUHS <pjw at google.com> said:
>>As I remember, the 11/70 was booted just as John describes. One keyed
>>in a boot loader at the console.
>
>I'm pretty sure our PDP-11 at Yale had a boot ROM, so you just set
>the starting address from the switches and started it.
>
>Before that I toggled boot loaders into PDP-8's and I don't miss it.
>
>R's,
>John
>
>
>>
>>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
>>
>
>