A digital data acquisition system has been developed which obtains sarcomere length data from a contracting skeletal muscle fiber or cardiac myocyte. The design is such that it can be used on any computer system capable of data channel operation (direct memory access). The design has been implemented on both the PDP-11/34a (cardiac) and LSI-11 (skeletal) computer systems. The PDP-11/34a is able to acquire data at 700 kHz (2.55 ms/1728 element frame) while the LSI-11 is able to run at 492 kHz (260 μs/128 element frame), both in single-cycle DMA mode. This high-speed operation is made possible by real-time storage of the data into temporary memories and unloading of the memories via DMA as bus activity permits. Thus, problems with memory refresh signals are circumvented and data can be acquired continuously (278 ms of time for the PDP-11/34a and 100 ms for the LSI-11 at full-speed operation) while performing experimental control. The flexibility of the data acquisition program as well as the hardware design afford the user the ability to tailor the data acquistion rate to the physiological experiment of interest. Sample data are presented which illustrate the system performance.
ASJC Scopus subject areas
- Biomedical Engineering