Re: External RAMdisk

The problem with semiconductor is flash/eeprom
technology has a defined wearout.

Is the wearout tolled by number of writes ...

Writing flash/eprom is rough on the insulation
around the floating gate, thus the limit on number
of erase/write cycles. Reads don't.
See: http://en.wikipedia.org/wiki/Flash_memory

Does anybody know if sheer AGE is a factor?

Definitely, even if it's not in use.
Old ROMS are suffering "bit rot"
as the chip suffers electron migration.
See "Failure modes" of
http://en.wikipedia.org/wiki/EEPROM
Another effect is
http://en.wikipedia.org/wiki/Electromigration

The data *** for the Microchip PIC18f4550
claims at least 40 years data retention
for the flash memory.

I had never even thought of Flash memory as
a long term archival format!

My crystal ball is busted so I can't foresee
how long USB ports or adapters will endure.
Many "standards" are being phased out such as
- SCSI parallel bus (in favor of serial interfaces)
- RS232 serial ports (displaced by USB)
- Centronix/parallel ports (displaced by USB)
- IDE parallel bus (in favor of SATA)

I have many backups that are hard to read
- magtape (800, 1600, 6250 bpi)
- ST506 drives using MFM or RLL, at 1:1 or 1:3 interleave
- 8" hard drive with SMD interface
- QIC tapes of varying densities
- 8" floppies from SSSD to DSDD
- 5.25" floppies in 360k DSDD, 720k DSQD, 1.2M DSHD
- 3.5" floppies are now hard to read: no drives!
- 5.25" PD (PhaseDifferential) optical disks (not Magneto-Optical)

I avoided Zip, Jaz, Syquest and other removeable hard drives.
I pity the friends with 14" platters
(whether single platter pizza-box
or multi-platter diskpack)
since all those drive are long gone.

Now that time has passed what have people
really found about magnetic media fading?
Are floppy disks written 20 years ago
faded so they won't read?

It seems that the way they're stored is a primary factor.
Many have rotted (moisture).
Some failed from poor materials
(oxide coating falling off due to bad binder).

Somewhere I saw comments that the biggest
problem for data archives is not the media
itself, but the complete lack of a working
drive that can still read it.

Such stories get great publicity at times
particularly a recent one about NASA tapes.
But there were allegedly archives of those tapes
on newer media so it was not such as disaster.

I've got to wonder if there's a "universal tape drive"
that magnetically scans the tape instead of
depending on a tape head with pre-defined heads.
Even if it's slow, it's only got to read the tape ONCE.
It would lovely if it could grok linear and helical tracks,
analog or digital, video or data, etc.

If you have a fabulous collection of 8" floppies
and could not find any working 8" DSDD drives
it could be a dead end.

That's why I'm active with MARCH:
the NJ computer museum at Camp Evans
(often mistaken for Ft. Monmouth), now the InfoAge museum:
http://www.infoage.org
http://midatlanticretro.org/

We're keeping the old iron running!
I personally have several 8" DSDD drives ready to run
in case of data retrieval.

What's the real long term life expectancy
for burned CD's vs RW CD's vs masked CDs and DVDs?

Apparently not as good as the manufacturers claimed.
I just read about a scheme to store error correcting codes
for DVDs on a separate medium (flash drive?)
or repeated on the optical medium itself
to try recovering from layer-rot
as the outer edge goes bad first.

The best bet for museum class archival
would probably be multiple copies on
various media, including data migrated
to newer technology as systems
upgrade into the future, right?

The Smithsonian and USA Library of Congress
have study groups exploring that.
One leading technology is ultra-fiche:
essentially superDuperMicroPhotography.
That way, only a microscope is needed to read it.
No need to know data organization
(partition table, file system organization,
file formats such as PDF, HTML, DOC).
And well made photos last for hundreds of years.

The joke's on us: trying to save
machine readable data is a losing battle.
Punched cards and paper tape are probably
readable via OCR without card/tape reader,
and printouts that haven't turned to dust
can be OCR-read (well, depending on the quality
of the printer. Some drum printers could not
keep a straight line.)

Whenever I see some post apocolypse sci fi flick
I imagine a few of the consumer DVD disks
survive the EMP that knocks out basically
all DVD players, rendering even the disks that
survive to be useless.

Or maybe they'll have a universal hi-res scanner
that reads the disk just as today's scanners
read documents and photos.

If it really comes to that, after a massively
diminished infrastructure and manufacturing
capability

Stock up on DuraCell batteries
because the electrical outlets will be dead!

The vacuum tube calculator circa 1970
and an old Russian microcomputer
linked to in here recently might
not look so quaint after the fall.

You're starting to sound like a SteamPunk romanticist
with all the speculation of what the industrial revolution
/could have been/. Fun stuff!
.

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