[TUHS] AP-3 minicomputer

[Paul McJones]

Computer History Museum curator Dag Spicer passed along a question from former CHM curator Alex Bochannek that I thought someone on this list might be able to answer. The paper "The M4 Macro Processor” by Kernighan and Ritchie says:

> The M4 macro processor is an extension of a macro processor called M3 which was written by D. M. Ritchie for the AP-3 minicomputer; M3 was in turn based on a macro processor implemented for [B. W. Kernighan and P. J. Plauger, Software Tools, Addison-Wesley, Inc., 1976]. 

Alex and Dag would like to learn more about this AP-3 minicomputer — can anyone help?