1980's Fairchild MB4113 Hard Drive Head Preamp

Images made through a microscope. All subject types.

Moderators: rjlittlefield, ChrisR, Chris S., Pau

Bob-O-Rama
Posts: 200
Joined: Sat Dec 06, 2014 6:46 am
Location: Allentown, PA, USA, Earth, etc.
Contact:

1980's Fairchild MB4113 Hard Drive Head Preamp

Post by Bob-O-Rama »

Big chonky hard drives from the 1980's would often have a small integrated circuit mounted on the head actuator arm to do analog to digital conversions, manage head select, write current, and pre-amplification - this reduced the length of analog signal leads to / from the heads, isolating them from RFI, and improving the SNR.

Image

These were about 1cm on the long edge and have a spider like arrangement of leads that would be soldered to mylar flexible circuitry, so these would be flying back and forth with the heads. Each chip included circuitry to manage 4 heads, addressable one at a time. You can see the separate analog sections along the top of the die.

To image the die at 20x required a 5x6 series of tiles. Because of the similarity of many of the features Hugin totally did an "amazing" job of building the panorama.

Image

It looks hopeless, but the fixup process is simple if just tedious. Go through each of the stills in hugin and check its connections to adjacent stills, eliminating stupid control points and adding more along the edges. This is the sort of stuff Hugin will do :shock:

Image

This was the initial result. There are some stitching artifacts, its not horrible, and using some futzing it can be made better.

Image

Note the little "MOVING" in the upper left, a hit that this chip would spend its life flailing back and forth.

Post Reply Previous topicNext topic