Emulating the Intel 4004
Scott Hamilton
Senior Expert in Emerging Technology
In continuation from last week, where I talked about emulation, I thought I would introduce you to some unique emulation projects. These are projects that are not at all popular, at least compared to the game system emulators, but still a lot of fun if you enjoy messing around with old hardware. I felt it appropriate to start my discussion of available emulators with talking about the emulators available for the first microprocessor, the Intel 4004.
The Intel 4004 was not only the first microprocessor, but also holds the record for the longest production run of a microprocessor in history. The Intel 4004 was in production from 1971-1986. Why did the 4004 last so long? There are two speculative reasons. The first is that the next generation processors required what is referred to in the industry as “glue logic,” meaning that in order to utilize them one had to design a lot of custom circuitry, mainly 7400 series decoders. The 4004 only required two chips, the 4004 processor and the 4001 ROM chip. The second was the ease of use, the 4004 had a tiny instruction set compared to the next generation at only 46 instructions. The primary use of the 4004 was in calculators and it sold for $60.
In the search for emulators that could let me play with an Intel 4004 processor, without buying one on ebay that may or may not work, I came across a few that are worthy of mentioning. The first is really cool because you don’t have to install anything to use it. If you go to http://e4004.szyc.org, the emulator loads in your web-browser and gives you a nice set of instructions to get started. I was able to run a simple memory test program on it in a matter of a few seconds following their instructions. The biggest issue with the online emulator was no easy way to keep my sample code without using copy and paste into a document.
The next emulator I loaded was a lot more difficult to get to run and requires a Linux based operating system, a C compiler, and the cmake toolset. It took me about 30 minutes to get it installed and basically working, but it turned out to be a little more fun to toy around with than the online emulator because it came with some more exciting examples of code. It was written by Leonardo Adilha Guarezi and released as open source at https://github.com/lpg2709/emulator-Intel-4004.
There are a few other open-source projects out there dedicated to the Intel 4004 but most of them have not been updated in five years or more and are unlikely to easily work without some code modification to support newer operating systems.
Arguably the best emulator, but also one of the hardest to get working, is housed at https://www.4004.com, where you can find everything about the historic chip. You can download full schematics and build your own with a lot of transistors, download the Verilog code, use a Field Programmable Gate Array to simulate the processor, about 100 times faster than the original, or even download the actual screens used during the manufacturing process of the actual chip. The site not only has an emulator for the chip, but the original source code for the calculator application that was the primary use of the chip in the 15-year run.
Until next week, stay safe and learn something new.
Scott Hamilton is an Expert in Emerging Technologies at ATOS and can be reached with questions and comments via email to sh*******@te**********.org or through his website at https://www.techshepherd.org.
