Rapid obsolescence of computer hardware has been a signature characteristic of the industry since its inception over 50 years ago. A one or two order of magnitude improvement in power, speed, efficiency, or cost per value has occurred every several years in areas such as CPU speed, memory chip density, storage device capacity, video processing rate, and data transmission rate.
Such monumental changes have a powerful obsolescent effect. New computers replace older ones not just because they are quantitatively faster, more productive, or higher in capacity (though those impacts alone provide considerable incentive to upgrade), but because they enable qualitative changes in the function of the device. Entire classes of computer uses and the software and file formats with which they were implemented, would not exist today had computing hardware not advanced to such a degree. These include uses such as CAD, digital imaging, audio and video production, simulation, and graphic web surfing.
Thus, new computing hardware opens the door to new and improved software, leading to software and file format obsolescence. The new software will not run on old hardware, further exacerbating hardware obsolescence. At the same time, the new hardware introduces other new technologies such as peripheral connections (e.g., Firewire and USB have replaced RS-232 serial and Centronics parallel ports) and storage devices (e.g., USB keys and CD drives replace floppy disks). These changes force older peripherals into retirement along with their compatible computers.
Types of Digital Storage Media
The nature of the physical media on which digital data is stored presents a major challenge to the preservation of digital content. The great variety of media types, their often rapid obsolescence from technological change, and their vulnerability to physical degradation all contribute to the problem.
There are three commonly used categories of digital storage media: disk, tape, and solid state. Within each category are many levels of subcategories, representing both integrated storage (drive and media as a single unit) as well as removable media.
Disk
- Magnetic (fixed hard drive)
- Magnetic (removable)
- Hard disk packs
- Floppy
- Zip, Jaz, etc.
- Magneto-optical (write-once, read/write)
- Optical (read-only, write-once, recordable, read/write)
Tape
- Open reel
- Cassette
- Cartridge
Solid State
- CompactFlash, Memory Stick, Smart Media (digital camera memory)
- USB memory key or stick, pen drives, keychain rives (portable storage up to 2 Gb)
- Flash drives (IDE or SCSI) using standard hard disk form factors; often for industrial or military use in adverse temperature, shock, or dust conditions (capacity up to 61 Gb)
Trends Contributing to Obsolescence
Several technological trends drive storage media obsolescence. These trends are evident from a browse through the Chamber of Horrors, and include:
Decrease in physical size
- hard drives (24" —> 1" over a 40 year period)
- floppy disks (8" —> 5.25" --> 3.5" over a 10 year period)
- optical media (14" —> 2" over a 20 year period)
Increase in storage capacity
- hard drives (5 MB —> 2 TB)
- tape cartridges (1.5 TB)
- 12 cm optical media (650 MB —> 60 GB)
Declining cost per unit of storage
- hard drives (most rapid)
- tape cartridges
- optical media (least rapid)
Other trends are less uniform for all media
- reliability (generally improving)
- fragility (variable)
- stability (generally improving)
- time to obsolescence (variable)