Hi, Lately I have been toying with the idea of building a stack machine computer. This would require a CPU that has more than the rudimentary stack operations of Push, Pop, etc. My research has led to the RTX2000 and RTX2010 CPU's that have been used for spacecraft and other specialized uses. These CPU's are practically impossible to find... at the moment there is one listing on EBAY for an ISA coprocessor card (with an RTX) for about $250. Does anyone have a suggestion for an IC that I might be able to source for tinkering?

Here is a link to an article about the RTX:

http://soton.mpeforth.com/flag/jfar/...1/article1.pdf