Traditionally, minicomputers have been used for the collection and analysis of data generated by flow cytometers. One reason is that, until recently, microcomputers, which would be more cost-effective alternatives, were not sufficiently developed to satisfy the unique demands imposed by flow cytometers. In order to overcome some of the deficiencies of early generations of microcomputers, several of the functions required for data collection, such as analog to digital conversion and data storage in static RAM have been performed """"""""external"""""""" to the computer which was used for the data analysis. 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 lntel 8OXXX 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 micro-computer. This system collected, processed, and conditioned the analog signals before acquisition by the micro-computer and effectively solved the problem of interfacing asynchronous and synchronous data conversion, acquisition and storage. The complete system, flow cytometer, interface, and micro-computer, has been in routine laboratory use for almost eight months. During this period, we have observed a small asymmetry in the acquired histograms. The cause was traced to the simultaneous occurrence of an analog pulse from the flow cytometer and the reset of the interface system. If the interface system completes reset while an analog pulse is present, the integrators were triggered and integrated the remaining portion of the pulse. These integrated pulses were always smaller than a fully integrated pulse. When the smaller values were added to the normal values, the histogram was skewed down toward the lower values. The problem is most severe at high flow rates.
