MIX and MIXAL?

Is there an interpreter for Knuth's hypothetical computer, MIX, together with an assemble for the MIX assembly language, MIXAL, available on any ARPA Network Host? If not, will not some Network Host make them available (cheaply)?--it would be considerable service to all of us who are students of the "Art of Computer Programming."

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     [into the online RFC archives by Helene Morin, Via Genie 12/1999]