The N82S147AF is a Fuse PROM, made by Signetics. This is a memory chip that can be programmed only once, which is usually done by the manufacturer of the circuit that it is used in. I got this chip from a circuit board out of some sort of telephone switching equipment.

This is the chip. It's housed in a ceramic DIP package, which provides better cooling properties than the usual black plastic packages.

Another benefit (at least for those interested in what's inside) is that these are very easy to open, using some mild violence.

When we put it under a microscope, we get a picture that's typical for memory chips. We see a regular grid of identical wires occupying most of the space. This is the area where the data is actually stored. The rest of the circuit takes care of the addressing and other housekeeping stuff.

Zooming in on the circuitry on the edge, we see complicated wiring patterns like this.

The data storage area is a very regular grid of horizontal and vertical lines. There is one bit of information at each intersection, and if you count carefully, you'll find that there are 4096 of these :-)