C.mmp

The C.mmp was an early MIMD multiprocessor system developed at Carnegie Mellon University by William Wulf (1971).

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 disk subsystem.

Each of the Compute Modules shared these communication pathways:
* An Interprocessor bus - used for distribution of system-wide clock, interrupt and process control messaging among the CMs
* A 16x16 crossbar switch - used to connect the 16 CMs on one side and 16 banks of shared memory on the other.

Since the PDP-11 only had an address space of 16-bits, an additional address translation unit was added to expand the address space to 25 bits for the shared memory space.

The operating system was called HYDRA. It was an capability-based object-oriented operating system, and was operated from a PDP-10 multi-user system. System resources were represented as objects and protected through capabilities.

Among the programming languages available on this system was a subset of ALGOL 68. This language was in fact more a superset than a subset, as the features supporting parallelism were vastly improved, to make good use of the C.mmp.

External links

* [http://research.microsoft.com/users/GBell/CGB%20Files/Cmmp%20Multi-Mini-Processor%20ComConference%201972%20c.pdf C.mmp - A multi-mini-processor, W. A. Wulf and C. G. Bell, C-MU 1972]