C.mmp

The C.mmp was an early MIMD multiprocessor system developed at Carnegie Mellon University by William Wulf (1971). The notation C.mmp came from the PMS notation of Bell and Newell, where a CPU was designated as C and a variant was noted by the dot notation; mmp stood for Multi-Mini-Processor The C.mmp was an early MIMD multiprocessor system developed at Carnegie Mellon University by William Wulf (1971). The notation C.mmp came from the PMS notation of Bell and Newell, where a CPU was designated as C and a variant was noted by the dot notation; mmp stood for Multi-Mini-Processor Sixteen PDP-11 minicomputers were used as the processing elements (named Compute Modules in the system). Each CM had a local memory of 8K and a local set of peripheral devices. One of the challenges was that a device was only available through its unique connected processor, so the I/O system (designed by Roy Levin) hid the connectivity of the devices and routed the requests to the hosting processor. If a processor went down, the devices connected to its Unibus became unavailable, which became a problem in overall system reliability. Processor 0 (the boot processor) had the disk drives attached.