Sometimes manufacturers of electronics can do weird things... Take a look at this:
I found this funny little thing in a pile of discarded computer equipment. It's a 'Lanport II' made by a company called Microtest (which seems to have been acquired by Fluke Networks). It was probably used to connect devices to a network through a serial port. On the left is a BNC connector used in old Ethernet networks, and on the right are two RS-232 standard serial ports. On the inside, it's a simple digital system consisting of a network interface chip, serial port drivers, a power supply, and a CPU to control it all. However, the people at Microtest had sanded off all the print from the CPU! Apparently they didn't want anyone to know what sort of CPU they had used. Well, sorry Microtest, but if you're so desperate to hide what you've used, I'll definitely go and find out :-)
There we are! We are obviously looking at a complex digital circuit here, probably a microprocessor of some kind. Now if we could only find some obvious markings...
...like these, it would be easy to see where this mysterious chip came from. Turns out it's an HD64180, a well-known Z80 derivative by Hitachi. Z80-like CPUs were used in lots of devices, and still are, including Nintendo's Game Boy, many calculators, industrial control equipment, and about 50% of all home computers from the early 1980s. Absolutely nothing to be ashamed of!
Another area of the chip. There are quite big transistors here, so we're probably looking at the drivers for some on-chip peripheral.