I came across an interesting single-chip processor in the General Instruments Microelectronics 1977 Data Catalog. They call it a Sequential Boolean Analyzer (SBA) and list it as "preliminary information", I have no idea if it was ever manufactured.
What's interesting about this chip is that it's a 1-bit RPN machine with many 30 i/o pins, a 16-level stack and supplementary storage. They specifically don't tell you if this is a microcoded design or implemented in hardware, but it's an interesting read from a theoretical design standpoint. Here's the pdf
I've never heard of an SBA before, are there other such implementations in hardware (or software)?
-Katie