For many years, physiological investigations have utilized the power and speed of analogue, digital and hybrid computers. Complex protocols often require the recording of large amounts of data in short periods, typically with simultaneous fine control of multiple experimental variables. Current systems often include data analysis in the same program which controls data acquisition. Although this is convenient from a package point of view, acquisition and analysis routines have different and sometimes conflicting purposes and requirements. This paper examines acquisition of continuous physiological signals by small dedicated computers in an attempt to separate these processes and to provide guidelines for computer selection, design and development.