24 Apr
2018
24 Apr
'18
4:01 a.m.
From: Clem Cole
To be honest, I really don't remember - but I
know we used letters for
the different partitions on the 11/70 before BSD showed up.
In V6 (and probably before that, too), it was numbers:
http://minnie.tuhs.org/cgi-bin/utree.pl?file=V6/usr/man/man4/rp.4
So on my machine which had 2 x 50MB CalChomps, with a Diva controller, which
we had to split up into two partition each (below), they were dv00, dv01, dv10
and dv11. Letters for the partitions made it easier...
The reason for the partition originally was (and it
must have been 6th
edition when I first saw it), DEC finally made a disk large enough that
number of blocks overflowed a 16 bit integer. So splitting the disk
into smaller partitions allowed the original seek(2) to work without
overflow.
No, in V6 filesystems, block numbers (in inodes, etc - also the file system
size in the superblock) were only 16 bits, so a 50MB disk (100K blocks) had to
be split up into partitions to use it all. True of the RP03/04 in V6 too (see
the man page above).
Noel
24 Apr
24 Apr
4:09 a.m.
New subject: /dev/drum
On Mon, Apr 23, 2018 at 4:01 PM, Noel Chiappa <jnc(a)mercury.lcs.mit.edu>
wrote:
No, in V6 filesystems, block numbers (in inodes, etc - also the file system
size in the superblock) were only 16 bits, so a 50MB disk (100K blocks)
had to
be split up into partitions to use it all. True of the RP03/04 in V6 too
(see
the man page above).
Venix 86 2.0 has a daddr_t of 16-bit as well. Venix is V7 based and is
limted to 32MB. It looks like the filesystem includes this limitation as
well. The winchester driver doesn't have the partitioning trick that the r*
drivers form the pdp-11, it seems.
Warner
2435
days inactive
2435
days old
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Warner Losh