P. Peterlin, J.Dempster* and R. Zorec
Institute of Pathological Physiology, 61105 Ljubljana, p.p. 11, and
(*) Department of Physiology and Pharmacology, University
of Strathclyde, Glasgow G1 1XW, Scotland
During the past decade, microcomputers have become an indispensible tool in physiological experiments, especially for the analysis of experimental data. In the field of electrophysiological signal recording, the optimization of price/performance quotient yielded a typical laboratory interface, built around a 12-bit A/C converter with required conversion rates around 30 kHz. Due to insufficient computer power in the past, such interfaces were usually designed to utilize complex circuitry, consisting of a DMA driver and/or a microprocessor with massive on-board RAM, all or which resulted in a higher price. However, the ever-increasing availability of low-cost, high-performance microcomputer diminished the need for complex and intelligent laboratory interfaces, since most of its functions can be performed equally well on the host computer. Therefore, it is possible to build a reduced-circuitry interface board which would perform as well as an intelligent interface board, only at a fraction of cost. We have decided to implement the already available library of electrophysiology analysis programmes (Dempster, 1989) to work on a low-cost A/D converter (IEVT, IFT/308) with 12-bit resolution and maximum conversion rate of 100 kHz (Burr-Brown, ADC774). Assembler programmes have been designed to link the interface and the electrophysiology analysis programmes to enable 35 kHz acquisition of data into computer RAM and 5 kHz rate for data acquisition into the hard disk. To increase the latter performance hardware modifications of the interface are considered. The former performance are also expected to be better with a higher speed of the computer.
J. Dempster (1989). Computer analysis of electrophysiological signals. In: Microcomputers in Physiology: A practical approach, IRL Press, Oxford.