This remote and narrow path result in an external access latency of 6 clock cycles, vs. one clock for the on-chip memory. Instructions are included for a quick hashed lookup in an on-chip table. We currently have two programming environments for the J-machine. Concurrent Smalltalk is a concurrent object-oriented language which looks more like Scheme than smalltalk. It offers support for concurrent distributed objects, a global address space, object migration, explicit object placement, inheritance, concurrency, futures, locks, etc.
All computation is done in user level message handlers.
This a really neat and underrated language, but it requires a bit of an adventurous spirit since it is experimental. Waldemar Horwat's revised CST manual is available by clicking here. Someone should port this to something like the CM-5 or T3D to expand its user base. Message-Driven C was developed by our collaborators at Caltech. The programming model is MIMD with asynchronous function call invocations around the machine.