hard drive history

transition: primitive ide drives

Seagate ST351A/X

Photo: Red Hill.

Seagate ST351A/X

The last 40MB drive made, and one of the better ones. The ST-351 was an odd mix of technologies: high areal density (only one disc for 40MB!) but an old-fashioned stepper motor. Presumably, this relatively high-speed but low cost combination is the reason why Seagate was able to keep the unit in production well after all the other 40GB drives had become uneconomic.

The "A/X" part of the model name is significant. It indicates that this drive had the unique feature of being jumper-setable for either eight-bit (A) or sixteen-bit (X) IDE operation — in other words, you could use it in an XT as well as an AT or 386.

Quite fast in its day and and reasonably reliable if well-treated, the ST-351 was ridiculously difficult to strap up for master/slave operation, and if you set the jumpers the wrong way, you blew the drive up!

The best 40MB drives of all were the more expensive voice-coil Western Digital Caviar and the beautiful little black IBM. The various Conner 40s were a mixed bag.

Data rate14 Mbit/secSpin rate3048 RPM
Seek time28msActuatorStepper
Platter capacity42.8MBInterfaceIDE mode 0
AT drive type17Form3.5" third-height
ST-351A/X42.8MB2 thin-film heads