The P/N 1948-series cable is an
enhanced IDE dual-drive cable, also
called Ultra ATA TPE or Ultra ATA-100.
It is designed for high-speed IDE data traffic between a motherboard
(or controller card) and up to two storage devices (hard drives or optical drives).
ATA-100 is the peak of the parallel IDE interface bus, which has since been
succeeded by the Serial ATA (or SATA). Unless you're working with
a legacy machine or digging up dusty old computers from the technology graveyard,
you're unlikely to encounter an IDE hard drive with the 80-pin interface.
...but if you do, and you need to plug it in, here's the cable to do so.