[TUHS] Panic! - Unix System Crash Dump Analysis companion CD-ROM

[segaloco via TUHS]

On Monday, April 6th, 2026 at 22:03, Warner Losh via TUHS <tuhs at tuhs.org> wrote:

> On Mon, Apr 6, 2026 at 9:42 PM r.stricklin via TUHS <tuhs at tuhs.org> wrote:
> 
> >
> >
> > > On Apr 6, 2026, at 3:17 PM, segaloco via TUHS <tuhs at tuhs.org> wrote:
> > >
> > > Weird disk that isn't a straightforward single track ISO9660?  I used to
> > run into that all the time with preserving optical media for game
> > consoles.  Our goto in that scene was bin/cue for funky optical media.
> >
> > More likely just that CD-ROM isn’t an archival medium. I’ve encountered
> > any number of e.g. early ‘90s Sun CDs with optical rot of one kind or
> > another. Oxidation of the aluminum layer, clouding in the polycarbonate
> > layer… It doesn’t surprise me to hear that, having encountered one bad CD,
> > several other copies had similar problems.
> >
> 
> The Solaris 2.0 Alpha binary CD that I have has been unreadable for at
> least 15 years.
> 
> Warner
>

I guess the question then becomes whether the multiple bad dumps have
the proper complement of good blocks between them to assemble a proper
image.  This may also suggest performing something like a bin/cue backup
that captures more sector information, that way you can also use that
metadata to better reconstruct a complete image.  This has been done for
a few video games where just enough good blocks could be pulled from
known-but-decayed specimens that the correct image could ultimately be
produced.

Heck just recently in the NES circle I chit-chat in, a few folks were
able to recover a lost bootleg title by visually analyzing mis-matched
cartridge traces to the particular ROM chip involved coupled with
analysis of a good dump of the title the pirate was built on, resulting
in determining which address and data bus bits were reversed and both
the precise bit twiddling on both data and addresses that was necessary
to reproduce a functional, playable copy of the game, and also the
banking logic that was buried under a chip-on-board blob.

This subject of creative recovery methods is quite interesting to me, I
often times worry that the video game and general systems history
communities don't have a lot of crossover because several of my go-to
"archaeological" techniques derive from practices in the video game ROM
hacking and emulation communities rather than the folks in institutions
with credentials archiving UNIVAC magtapes and Western Electric ROMs.

All to say I do love these moments when the oddball techniques from the
video game preservation microcosm are also applicable to the other tech
history stuff I appreciate.

- Matt G.