hard drive history

beginings: mfm drives of the 1980s

Microscience HH-1050

Photo: Red Hill.

Microscience HH-1050

Microscience was a high-cost, small-volume maker of quality hard drives back in the days when you didn't have to be a multinational giant to afford hard drive research and development. They made a range of beautifully crafted 5.25 inch voice-coil drives, all with a distinctive rippled top. The HH-1050 was the smallest and most common of them, and very fast for its day.

Notice the odd number of heads: voice-coil drives need to have positioning information encoded onto the drive itself, so that the heads can find the correct track. (Stepper drives just step in or out the required number of times and hope for the best.) Until the development of embedded servo technology around the end of the 1980s, all voice-coil drives had to sacrifice one complete surface for head positioning — you couldn't put data on the servo tracks. This meant that it was uneconomic to make small voice-coil drives: in a single-platter drive, you'd waste 50%, but in a big 4-platter drive, you only waste 12.5%. A few new drives still did this until about 1995.

Picture: Two MFM drives. The 5.25 inch Microscience HH-825 on the left was high-end class, almost equivalent to a Cheetah X15 a decade later. The little 20MB Miniscribe 8425 was an early 3.5 inch stepper drive, still mass-market but a cut above the big old 3650s and ST-225s. This one was manufactured on 24th August 1989. The Microscience goes back to June 1987.

Data rate7.5 Mbit/secSpin rate3600 RPM
Seek time28msActuatorVoice coil
Platter capacity16.8MBInterfaceRLL
AT drive type2Form3.5" half-height
HH-105042MB5 thin-film heads1987