Rememberance of Things Past   Leave a comment

And down the rabbit hole we go….
Naturally, after finding the old EPROMS, we looked around the numerous dusty corners and buried shelves to see else what we could find. Sure enough, we found cases of old chips that were purchased over the years as spare parts for lab apparatus. Based on the dates of the EPROMs and given the volume of spare chips, we expected that by restricting our interest to items manufactured before 1985 would result in a manageable number of examples.


We needed to restrict our interest to items manufactured prior to *1975*, which essentially corresponds to the paleolithic era of integrated circuits.

Here are few examples of items we uncovered:


The date of manufacture is given by the 4-digit sequence below the part number, in the format YYWW. That is, the chip on the left is a Motorola MC832P (a 4 input NAND gate) manufactured on the 44th week of 1966. The chip on the right is a Motorola quad 2-input NAND gate array manufactured on the 12th week of 1969.

Other chips are not marked as clearly:


These two chips are part of a series (the 4000 series) manufactured by RCA (the RCA COSMOS chipset). The date code is a different format than above, but based on the packaging these were likely made in 1968 or 1969.

Then there are these examples:


Where we can determine the date of manufacture, but cannot determine either the function (the ITT chip above) or the manufacturer (the decade counter below).

Let’s be clear- we are conservators, not barbarians. We are not going to mindlessly destroy these items, even though they have very little intrinsic value. We will proceed in such a way as to minimize the number of decapsulated chips, minimize any damage caused by decapsulation, and maximize the educational value obtained by displaying the interior circuit. This honors the historical value of these devices. We’ve also only begun looking around the storage area- there are piles of solid state devices we suspect are even older, perhaps all the way back to the early 1960s and late 1950s.

We end this post with images of a more modern chip- a KFG8GH6Q4M, a 8Gb NAND RAM manufactured by Samsung in 2008. Again, the lenses used are the Luminar zoom, 100mm, 40mm, and 16mm (oblique reflected illumination), then using epi-illumination, the 16mm and a 40/0.85 epiplan:


The feature sizes are small enough to cause diffraction (the parallel lines act like a diffraction grating).

By contrast, the 1602A at 40/0.85 (that is, the same scale as the last images above) looks like this:


To get this image, since we didn’t want to remove the cover, we used a 40x/0.85 dipping objective, which has a long enough working distance to reach the chip surface. But we can’t go any higher in magnification with the EPROMS, since our 100/1.47 NA lens is an immersion lens with a very short working distance.

What a difference 40 years makes….


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