Networked VAX/LSI/CAMAC Data Acquisition System Development

Recent development of the Caltech data acquisition system installed in 1981, which runs on a VAX-11/750, a Peritek Q-bus network, LSI-11s, and CAMAC, is described. In this system, the DEC VMS and RT-11 operating systems are supported on the VAX "host" and LSI-11 "front-end" computers by a VMS device driver and network host program, and a bootable RT-11 device driver. Network "utility" and "control" programs provide general purpose support for communication between front-end and host software. Data acquisition software tools are provided for writing programs to run nuclear physics experiments. A system similar to Caltech's was installed at the University of Rochester in 1982. The network has been tested for speed and real-time response. After including all software overhead required by data acquisition, it was found that the system cOutld transfer buffers and acknowledge their receipt at a net speed of 127 KB per second with a 35% load on the host computer. The network software is currently being rehosted on Ethernet hardware at Caltech in a multiple host - many front-end computer configuration. Compatibility with the current Peritek network software will be maintained.