Computer-software-controlled placement of cells onto microscope slides is advantageous for quantitative optical microscopy. Cell detection, indentification, and placement have been implemented on a software-controlled flow sorter. Computer hardware timing latencies that comprise the dead times of the system are sufficiently short (10 micros) to allow adequate dealy of cells for sorting. Operating system timing latencies (150 micros) are also short enough for low-rate sorting. As a result of the low cost of computers and because formats for cell placement are still controversial, software control is desirable somce it provides the flexibility to implement multiple variations for cell detection, identification, amd sorting.