hard drive history

finding the formula: ide as we know it

Alps DDR100

Photo: Red Hill.

Alps Electric DRR-40

A very odd little drive. Alps Electric haven't made hard drives for many years, though they continued manufacturing floppy drives for a long time, and laptop touchpad pointing devices for years after that, but these little 40MB units were always good performers. They were very small and thin, especially by the standards of the day, and used an odd-ball small power connector like a 3.5 inch floppy drive. As usual with early IDE drives, they didn't master/slave well. There were identical-looking Alps 105 and 200MB drives too.

The Alps drives were some of the first ones to use sector translation to get more than 1024 tracks on a disc. This used to cause troubles with the IDE 'identify' command, which was employed by auto-detect BIOS or drive utility programs to ask the drive what its correct parameters were (heads, cylinders and sectors per track). The Alps 40 returned its actual parameters, where more recent drives returned their logical parameters. So, if you auto-detected an Alps 40 using a standard pre-LBA BIOS, you had to halve the cylinder count and double either the heads or the sectors per track. (Or, for that matter, use any other three CHS figures that added up to the correct size and didn't violate the CHS maxima: 1024 cylinders, 16 heads, 63 SPT.) It's been some years since we've seen one of these.

Estimated performance0.45ReliabilityAA2
Estimated data rate15 Mbit/secSpin rate3600 RPM
Seek time19msActuatorVoice coil
Platter capacity10.7MBInterfaceIDE mode 0
AT drive type17Form3.5" quarter-height
DRR-4042MB2 thin-film heads