Just another random chip photo passing by on the slideshow. This was the PCB on my first multi-gigabyte hard drive, a 2-gig Seagate Medalist (ST32122A). If memory serves, it came with the Pentium 166 I acquired shortly after the start of my second semester in college (the good old 386 was no longer cutting it).
Googling the numbers on the chip reveal that this is a “high speed CMOS static RAM” chip, though I couldn’t find any further information as to what it was used for. Since it’s a CMOS chip (and there is a battery-looking thing on the PCB) I would guess that it stored drive parameters and that it was programmed at the factory. Most likely the different capacity drives in the same line shared the same PCB, and they just programmed this chip as appropriate. It could also be cache memory, but that guess is just a stab in the dark.