A new system, combining the advantages of cheap portable recording units with the power of computer analysis, has been described. The recording medium is quarter inch magnetic tape which is used on an ordinary domestic tape recorder. An electronic scanner fitted inside the recorder case accepts up to 40 inputs from a keyboard, which can be of any design, and converts these into a time-multiplexed form suitable for recording on a single track of the tape. The recording process incorporates a check system to detect tape errors, and has a basic time resolution of 0.1 sec. The cost of the components of a complete recording unit (keyboard, tape recorder, scanner) is less than £200; thus, sufficient machines can be available to avoid problems of sharing. Further, a battery powered system could be used for field work, because the way in which information is encoded makes the timing of the system independent of variations in tape speed. A small computer (PDP8/S) is programmed to transcribe the original recordings into permanent condensed form on paper tape by punching information only at times corresponding to changes in the keyboard. Additional programs analyse data from the paper tape transcriptions. Some specialized decoding hardware has been interfaced to the computer to perform the preliminary operations of recovering signals from the tape, in order to reduce the demands on the computer. Transcription time is reduced by replaying tapes at up to eight times the original recording speed and, if necessary, detailed results can be obtained within 30 minutes of completing an experiment.