Backups [was Re: Is tape dead?]

Johnny Billquist bqt at
Mon Sep 21 09:31:35 CDT 2015

On 2015-09-21 15:15, Noel Chiappa wrote:
>      > From: tony duell
>      > In some cases it should be possible to write a machine code program
>      > that executes on 2 processors with wildly different instruciton sets.
> I have this bit set that I was told (or something, the memory is _very_
> vague) that early versions of the KL-10 had this hack; the root block on the
> disk was the boot block both the PDP-10 and the PDP-11 front end machine, and
> the first instruction or two was very cleverly construced and sent the two
> machines different ways. Alas, I looked in the front-end PDP-11 code (in the
> KLDCP; directory) and saw no signs of this, so maybe it was an urban legend?

I suspect that would be an urband legend, as the KL10 is booted by the 
PDP-11, and does not, on its own, start reading something from the disk 
to start executing. Or at least that is how I remember things...

However, the PDP-11 FE filesystem exists, as a plain file, in the 
PDP-10s file system (TOPS-10 or Tops-20).


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