In order to overcome some of the deficiencies of early generations of microcomputers for data collection from flow cytometers, several of the functions such as analog to digital conversion and data storage in static RAM, have been performed 'external' to the computer. In addition, Mixed-flow cytometry systems in which data are collected with a minicomputer and analyzed with a microcomputer have been developed. However, these approaches are not cost effective and do not effectively use the improved capabilities of available microcomputers. With the evolution of the Inter Ass family of processors, reliable peripherals, and a variety of powerful compilers, it has become feasible to develop a relatively inexpensive microcomputer-based data collection and analysis system for flow cytometry that performs as well as, or better than, minicomputer-based systems. Earlier we developed an electronic interface system which linked the analog signals from the four preamplifiers of the flow cytometer to the microcomputer. This system collected, processed, and conditioned the analog signals before acquisition by the microcomputer and effectively solved the problem of interfacing asynchronous and synchronous data conversion, acquisition and storage. We found that when analog signals occurred simultaneously with the reset of the integrators only partial integrations were obtained which skewed the cell histogram. A trigger hold-off circuit in the analog detector section eliminated this problem. The complete system, flow cytometer, interface, and micro-computer, has been in routine laboratory use for almost two years. During this period, we have studied in detail the timing of the various interface and computer tasks to identify where improvements in data throughout were possible.
