IEEE Transactions on Nuclear Science, Vol. NS-32, No. 4, August 1985 DATA GENERAL 32 BIT COMPUTER BASED AQUISITION SYSTEM AT THE PRINCETON UNIVERSITY CYCLOTRON R. T. Kouzes and M. Karisson Princeton University, Department of Physics, Jadwin Hall, P.O. Box 708, Princeton, NJ 08544 ABSTRACT A new data acquisition and analysis system based on Data General MV/10000 and MV/4000 32 bit minicomputers is being developed at Princeton. The CAMAC based system uses a Bi-Ra interface controlled by the data acquisition program ACQUIRE. The MV/4000 acquisition computer is tied via Ethernet to the MV/10000 analysis computer. I. INTRODUCTION The Princeton University Cyclotron Laboratory is a facility for the investigation of nuclear physics phenomena at low energies. During the thirteen years of operation of our present cyclotron, the diversity of experimental work has steadily increased, making new demands for data acquisition and analysis. The past few years have seen growth in our research program characterized by multiple simultaneous experiments -- each requiring new instrumentation of ever increasing complexity. In 1976, the Sigma 2 computer that had been used since 1969 was replaced with a system based on a Data General Eclipse S/230 computer.C1*2133 This system will continue to be used until the new one is fully implemented. The limitations of the 16 bit system will first be outlined, followed by the desired system configuration. I will then present the reason for choosing the Data General MV system over the more common DEC VAX system. II. LIMITATIONS OF THE S/230 SYSTEM The computational needs of the cyclotron laboratory divide into two areas -- each involving differing hardware and software features. The first task is data acquisition which requires high speed real time processing capability with the availability of interactive replay of event data. The second is scientific calculation requiring large memory and disk space, and high speed floating point processing. In addition, convenient multiuser program development facilities are required. The Data General 16 bit Eclipse S/230 has 256K bytes of memory, 80 megabytes of disk storage, and two 800 BPI tape drives with a data acquisition interface of in-house design and construction. This one machine has been used for all of the Cyclotron Group's computational and data-taking requirements. For data acquisition, the S/230 is primarily limited by the number of parameters per event (eight), the memory available for histograms (16K words); and the number of simultaneous experiments that can be handled (one). For computation, the S/230 system is limited most importantly in program size (32K words), available disk space, and lack of efficient timesharing. This means that complex programs such as shell model codes cannot be implemented, while a larger class of programs have been implemented with a great deal of software development. Much of our computer time is used for Monte Carlo calculations. such as atomic beam machine transport properties which could be performed far more efficiently on a larger machine. III. ACQUIRE DATA ACQUISITION PROGRAM The data acquisition program used with the S/230 system is ACQUIRE which is based on program DERIVE, the data acquisition program developed by the Author for the Indiana University Cyclotron Facility. ACQUIRE allows for creation of up to forty arrays of one and two dimensionality for sorting ADC data with zero offsets, variable gains and up to ten side conditions (gates) per array. Event mode recording of data for later processing is provided as an option (most of our experiments are sorted online). In addition, ADC values may be quadratically transformed with division before sorting. Such a capability is useful, for example, in making position dependent corrections to scintillator light output. The program also provides for printing. plotting. data analysis, dumping to tape. logging of commands, and entering repeated command sequences1 among others. Several data taking modes are predefined including spectrograph data analysis with four windows on a two dimensional particle identifier. Data rates are mode dependent, but are typically limited to the one-to-twenty kilohertz region. An important feature of this data acquisition system is the ability for experimental control via the computer. IV. REQUIREMENTS OF A NEW SYSTEM A few simple criteria were established for selecting the basic system configuration: 1) Two independent processors should handle the computation and acquisition, coupled by a communications link. 0018-9499/85/0008-1363$01.00 © 1985 IEEE 1363