The SAB8252C is an HDLC controller, whatever that may be. Probably some sort of I/O controller from an old, forgotten digital system. It was made by Siemens, who have since spun off their semiconductor business to form Infineon. For the microscopist's convenience they have put it in a ceramic package with a metal lid that simply pops off when heated.

The top left corner. This is a typical picture of a relatively complex digital circuit (microprocessors, I/O controllers, multifunction ICs etc), showing lots of complicated machinery organized into blocks. These blocks are connected to each other with a lot of wires (called interconnect in IC lingo).

A bit more to the right. There are again lots of wires, and some other interesting things too. Let's look at them more closely:

Here is the manufacturer's name, which is a very common feature on ICs. The four crosses on the left are called alignment markers. These are used to make sure that all the layers that the chip is made of are placed exactly on top of each other. If the crosses line up with each other, then the layers are aligned correctly and the chip should be OK.

This is a close-up of the top-right corner. The square things are metal pads used for testing of the completed chip. There are a few basic structures in between the pads, like transistors, logic gates, resistors or something else. A test engineer can then use a piece of equipment called a probe station to measure the characteristics of these devices. This probe station contains a couple of sharp pins that can be placed on the pads. It can then apply voltages and currents to the devices and measure their performance. Measuring the performance is very important for quality control, because the exact characteristics will vary with each batch produced, and the manufacturer must make sure that they stay within certain limits.

Another thing we see here are letters that identify each layer of the chip (or, more accurately, each mask). 'd' and 'f' are clearly visible, but if you look closely you'll see 'a', 'b', 'c', 'e', 'g' and 'x' as well.