How to read v6 distribution tapes?

[Dennis Ritchie]

Roy Smith wondered about how to look at v6, which exist on tape as
RK05 disk images.  Here's how we do it.  It's instructive of
something--I'm not sure quite what, but it makes an interesting demo,
and it is a useful way to keep these archives.

We transferred the disk images to big single files.  Norman Wilson
wrote a file server that understands the v6 disk format (512-byte disk
blocks, 32-byte inodes, 16-bit disk addresses).  Thus we can mount
this disk image as a file system and poke around in it.

Incidentally, we still have a few vax 11/750s, with the pdp-11
compatibility feature.  So, from such a machine I can do

	cd /n/bowell/usr/src/history/v6/bin/bin   # move to v6 /bin
	compat sh				  # start v6 shell

and get a `%' prompt.  These commands change to a directory on another
machine, which contains an interpreted Sixth Edition file system, and
run the Sixth Edition shell.  Many of the commands there work.  E.g.

  % ./size sh
  4992+880+1408=7280 (16160)
  % ./date
  Thu Feb 14 00:46:32 EST 1991
  % ./dc
  10k2vp
  1.4142135623

Doing this induces a somewhat creepy feeling.

	Dennis Ritchie
	dmr at research.att.com
	att!research!dmr