The State of Storage As storage media grows denser and more complex over time, it's worth remembering that older formats were sometimes far more durable. Sometimes.
Paper tape, for example, can be prodigiously long-lasting. Unless, of course, it receives some unwanted attention.
"I did once open a box to find a moth had nested inside and feasted on the paper," recalled Andrew Herbert, chairman of trustees at the National Museum of Computing (TNMOC). The result was that the tape was too fragile to handle and essentially useless.
Herbert's interest is in machines from the 1950s, '60s, and '70s, and he has encountered a lot of software stored on punched paper tape. Wound loosely, there's a good chance the code can still be read. Wound tightly, it might get brittle. Folded, there's a chance it might split along the fold lines.
That said, damage to a tape doesn't necessarily mean it's a write-off. "If there are tears or mispunched holes, then if the data format is known, it is often fairly easy to reconstruct the original, especially if there was parity or a checksum."
Delwyn Holroyd, a volunteer at TNMOC who leads the team that restored and maintains the marvellous 1950s WITCH, also has experience with paper tape, which he warned does tend to deteriorate with use. "The WITCH paper tape readers use spring-loaded metal pins to sense the holes in the tape," he explained. "Over time, the pins wear through the tape, so we duplicate the working tapes every few months."
Holroyd also works with punched cards, which he noted can last indefinitely in the right conditions. "The main challenge," he said, "is to avoid dropping a card deck and mixing up all the cards."
And then there's TNMOC's ICL 2966 mainframe. Holroyd is all too familiar with the temperamental disks used by the machine. "The 2966 originally used exchangeable 80 MB and 200 MB disks where the heads fly above the surface of the disks on a cushion of air just a few microns deep, much smaller than dust or even smoke particles," he told The Register.
Any contamination could result in a head crash and a potential catastrophic failure. "They were never terribly reliable when new," he added, "so we have no chance of operating them at the museum without frequent disasters."
And magnetic tape? "Another problematic storage medium," said Holroyd. While not such a problem with older tapes, later ones (from the '70s and '80s) suffer from "sticky tape syndrome" when the binder used to glue the magnetic oxide to the plastic tape backing absorbs moisture, causing the tape layers to stick together.
"Attempting to play a sticky tape can tear off chunks of the oxide and cause irreversible data loss."
The answer? "Bake the tape at around 50-60°C to drive the moisture out, although this is only a temporary solution. It takes many hours to treat the typical large open reel half-inch tapes used by mainframes and minis."
At the Centre for Computing History, Adrian Page-Mitchell reported challenges with 3.5-inch floppy disks, where brittle plastics and off-gassing can affect the media inside. Page-Mitchell also collects LaserDiscs, and told us that the disc rot phenomenon, where optical discs degrade over time and become unreadable, was highly manufacturer-dependent. He claimed that one well-known manufacturer's facility "was just not up to the job, and contaminants cause disc rot in those. Other ones, such as Pioneer, still play perfectly today, as their manufacturing was far more robust."
Page-Mitchell noted that some obsolete formats, such as HD-DVDs from another manufacturer, were rapidly failing, and certain types of CDs could no longer be read.
A challenge with storage is the longevity of the media and the availability of hardware capable of retrieving it. While paper tape and punch cards are long-lasting and can be read by enterprising enthusiasts of today, modern densely packed SSDs and spinning disks might present more of a challenge for the archivists of tomorrow. ®
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