Real time processor in JT-60 data processing system

Real time processor, RTP, is a basic subsystem in the JT-60 data processing system and plays an important role in JT-60 feedback control utilizing various diagnostic signals. An original mini-computer system was replaced in 1994 with a workstation. It has 2 CPU's with a real-time parallel UNIX. During the experiment, one CPU communicates with the main computer synchronized with the experimental sequence, and the other executes a real-time process with 1 ms clock. RTP has been upgraded to a compatible RISC workstation with a faster A/D converter in 1997 in response to increased requests of handling the increased signals in more complicated manners. After this upgrade, an elapsed time is reduced to ∼75% and an I/O time is now dominant. To reduce a CAMAC access time, we try to use a reflective memory for the data transfer. Now RTP handles six kinds of signals to control an electron density, a neutron emission, an electron density and a radiation in the divertor region, and a neutral pressure. RTP will handle five more kinds of signals this year and be used for an advanced control with more complicated processing.