[pups] V7 vs RX50 (was Getting a MicroPDP-11 Running)

Norman Wilson norman at nose.cs.utoronto.ca
Thu Jul 27 23:48:45 AEST 2000

400KB floppies, or even 1.4MB ones, may seem tiny now; but they should
hardly be undersized for a bare-bones V7 root file system.  Remember
that disks weren't all that big in the late 1970s, and that one of the
important fixes in V7 was that it became possible to make a file system
bigger than 32MB.

The V7 version of the `Setting Up UNIX' paper doesn't say just how big
the root file system dump is, but the instructions say the file system
itself should have 5000 blocks: about 2.4MB.  If the dump was that big,
it would have taken just over 6 RX50 diskettes.  (But it probably wasn't
that big, because there must have been a good bit of free space in the
standard root--/tmp was there too!)

I once ran a stripped-down V7 off a single RK05 (2.5MB including swap)
for several days, during an air-conditioning crisis.  The system wasn't
fully-functional, but there was enough there to let the secretarial staff
keep up with their typing, and even run troff.

The real trouble with the RX50 is not so much the size as the speed:
the damn things are painfully slow.  I sometimes boot my V10 MicroVAXes
from RX50, as part of an experimental Jumpstart-like installation scheme.
The bare-bones installation environment requires only two floppies; the
real nuisance is that it takes several minutes to read them.

And, of course, V7 doesn't have an MSCP driver, since MSCP didn't hit the
streets until 1982 or so.

Norman Wilson

More information about the TUHS mailing list