The MODCOMP II was introduced in 1972 according the MODCOMP reference manual. The last reissue of the manual was in 1976. MODCOMP is short for "Modular Computer". MODCOMPs were often used in real time laboratory and manufacturing applications. They were considered highly reliable systems. This system and a second MODCOMP system are now located at the Computer Museum of America (CMoA).
The MODCOMP II/12 below was "rescued" January 12, 2007 from a major scientific laboratory where it had been marked as "Salvage". A good friend of mine from the lab told me about it - and went throught the process of having it "salvaged" to me. I spent about a day cleaning up the CPU chassis. As you can see below, I have not yet begun cleaning up the I/O chassis.
Note that each "module" of the system folds out - making it relatively easy to get to the wire wrap. The CPU chassis consists of two CPU "modules" and the two 32K core memory "modules" (for a total of 64K of memory). The CPU is an 800 nanosecond, 16-bit computer having many characteristics of 32-bit computers. The CPU is controlled by execution of 40 bit microinstructions stored in ROM. The microinstructions are accessed and executed in 267 nanoseconds; i.e., three microinstructions are executed per 800 nanosecond memory cycle.
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