Larry McVoy lm at mcvoy.com
Sat Sep 14 01:23:45 AEST 2019

On Fri, Sep 13, 2019 at 06:00:09PM +1000, Peter Jeremy wrote:
> On 2019-Sep-13 15:54:32 +1000, Dave Horsfall <dave at horsfall.org> wrote:
> >On Thu, 12 Sep 2019, Larry McVoy wrote:
> >> But here is an SCCS win.  SCCS has a 16 bit ignore the carry bit 
> >> checksum over the whole file.  RCS has none of that.
> >
> >Giggle...  I found I could actually *edit* an SCCS file, provided I reset 
> >the checksum to zero (it was then recalculated).
> I think that was deliberate.  ISTR editing SCCS files and repairing the
> checksum as well, though I don't recally exactly how.

bk admin -z file.c

and I'm pretty sure that is sccs compat.

> >> B) NFS errors.  So all NFS implementations, Suns included, had a bad 
> >> habit of returning a block of nulls.  I dunno why but that is a thing. 
> >> The SCCS checksum would detect that.  RCS and CVS did not have a 
> >> checksum so when NFS returned garbage, they were happy to return that to 
> >> you.
> >
> >I believe that NFS is much more reliable now (yes, it used to be awful).
> NFS ran much faster when you turned off the UDP checksums as well.
> (Though there was still the Ethernet CRC32).

Living dangerously.

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