The DS80C400 is a very interesting little chip made by Maxim. It was actually designed by Dallas Semiconductor (hence the DS prefix), a subsidiary of Maxim. They continued to use the Dallas name for a couple of years, but stopped doing this in 2007. The 80C400 is a microcontroller based on the classic 8051 design, which is by far the most popular microcontroller ever made. Dallas managed to upgrade this simple 8-bit system to run at 75 MHz, and included a 10/100 Ethernet controller with full TCP/IP stack, a CAN bus, three serial ports, a math accelerator and 64 KB of ROM. If all this doesn't mean anything to you, it's just completely loaded with features. A bit like having a VW Golf with not just a sunroof and cruise control, but a full Jacuzzi and a champagne bar :-)
I thought I'd taken a picture of the chip in its package, but I can't find it anywhere... So here is a photo of the inside, which just fits in the viewable area of my microscope. The layout is neatly divided into blocks. Two blocks of memory in the middle (yellow and pink) and blocks of digital logic around them. One of these probably holds the Ethernet controller (which is quite a complicated piece of kit), another might hold the 8051 core, and the rest is taken up by all the other peripheral components.
The memory area in the middle. It's the same area that was yellow in the picture above, but it's now pink because of slighly different illumination. There's a little spec of dirt there, which is unfortunately unavoidable unless I move to a cleanroom :-)
Digital circuits. These were clearly made by a computer: you just type some code, and the computer combines all the logic gates to create a circuit that does what you want.
A nice little message from the design team. Dallas apparently makes Faster and Smarter chips. And they're not bragging, this chip really is very fast and very smart.
A little further we find Maxim's logo. Along with it the initials of the design team, and a couple of mysterious codes: 15B1/80AZ, 17B1/88AZ, 57B1/93AZ and 22B1/96AZ. My guess would be that these refer to a number of company milestones, achieved in several years ('80, '88, '93 and '96) in Arizona (AZ). Maxim has Technology Centers in Phoenix and Tucson, perhaps this chip was designed there.
This high-magnification close-up of the memory area shown above looks really pretty. These trees connect the memory rows and columns to a bus running below it.