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The increasing demand for laboratory investigation of patients has created many new problems for the pathologist, not least of which is the difficulty of handling all the data involved. Manual data processing systems are still operating satisfactorily at present but there are sound reasons for considering the use of automatic data processing in the future (Flynn, 1966).To enable data to be handled entirely by mechanical or electronic means a language is required which can be written, recognized and reproduced without the aid of the human eye. In the punched hole language which is commonly used for this purpose there are only two symbols, a hole or no hole, and different numbers and combinations of these symbols are used to represent each 'character', that is each letter, digit, or sign. The machines detect where holes are present and convert the information into electrical impulses.Getting information into suitable form for machine handling represents one of the major obstacles to the use of automatic data processing systems. Of the two steps that are involved, namely, the collection of significant data and the coding of such data, the second presents the greater difficulty and is often dependent on specially trained personnel. Because a high proportion of our analyses are now performed with the Technicon AutoAnalyzer, we have concentrated in the first instance on devising equipment which will automatically collect data from these instruments in machine-readable form. We have collaborated in designing a suitable analogueto-digital converter which when attached to the AutoAnalyzer recorders automatically finds the peaks during the run of analyses and records their height on punched paper-tape ready for direct computer entry. In this paper we describe the equipment and report on our experience with it; preliminary accounts have already been published (Flynn, 1965a and b). Details of how a computer has been programmed to process the data captured by the analogue-to-digital converter will be described elsewhere.Received for publication 9 August 1966. DESIGN CONSIDERATIONSThe basic requirement of the analogue-to-digital converter equipment is that it should automatically select, code, and store for subsequent computer processing the significant part of the analogue information presented on the AutoAnalyzer recorder. The equipment therefore incorporates facilities for recognizing the peaks, quantitating their heights, converting the values to binary form, and punching the coded information on to paper-tape.It is not possible to select peak values by a timing device because the intervals between them are not quite constant for a given rate of sampling of specimens, and therefore peaks have to be recognized in some way. This could be done electronically by monitoring the magnitude of the voltage signal to the recorder, or mechanically by following the direction of rotation of the potentiometer shaft. The latter method has been selected because of its relative simplicity. The existence of background noise on the recordin...

Eelven urine samples from normal subjects inhibited the formation of calcium phosphate. In all cases the activity of the urine was identical with that of an artificial urine having the same concentration of urea, creatinine, sodium, potassium, magnesium, calcium, ammonia, sulphate, chloride, inorganic phosphate, citrate, isocitrate and pyrophosphate, and the same pH.