4BSD file system structure

[Bill Pechter <pechter>]

In article <1602 at minyos.xx.rmit.oz>, rcodi at chudich.co.rmit.oz (Ian Donaldson) writes:
> chris at mimsy.umd.edu (Chris Torek) writes:
> >In article <3410 at netcom.UUCP> hinton at netcom.UUCP (Greg Hinton) writes:
> >>If so, doesn't the presence of the boot block throw things off?
> 
> My guess that the 4.[23]BSD way of putting the boot block into the first
> part of the filesystem stems from the fact that:
> 
> 	1) at the time that the FFS was introduced, there was no
> 	   4BSD disk labels (except from some vendors such as Sun),
> 	   and the VAX prom may have booted VMS this way (I'm not
> 	   sure about this). 
> 	   The 4.3-tahoe release added the labels.
> 
> Care to comment Chris?
> 
> Ian D


I guess I ought to jump in here -- there was a boot prom on Vax 11/750's that
read in the boot block from cyl 0, sector 0, track 0 -- but that was the only 
Vax that did that.  The rest used the console floppy or TU58 DECtape to read
in a console program or loader that did the initialization.

It was a pretty limited (i.e. AWFUL) way to do things.  DEC had to go to 
the console tape mode on the 11/750 when they went to Vaxclusters...

However most 11/750 owners on Unix used the bootprom to boot...

There were up to 4 proms available -- labeled A through D.  There was
usually an RH780, RK07, TU78 and RA81 rom on the later Vax 750's.
The minimum was either RH or RK07 with TU58.

We did the rom boot when I was at Eaton on SysV Rel 2 and I know others using
4.2bsd did the same.  The TU58 took up to 3-5 minutes to load.  DEC clusters
running VMS also had to download microcode to the CI750.  Also, I seem to 
remember some SysV Unix sites had to put in a Translation Buffer patch 
sometimes from the TU58 on boot.

The 11/730 was worse -- it had 2 TU58's -- 1 with microcode, one with
console and boot.

Excuse faulty memory -- it's been about 2 years since my last 11/750 --
and about 3 since my DEC Field Service Days...


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