Abstract: A subranging A/D converter generates high and low voltages using first and second DACs. A voltage divider receives the high and low voltages to generate plural reference voltages. A bank of comparators compares the analog voltage which is to be converted to each of the reference voltages, and a clocked logic circuit generates an intermediate digital signal indicative of the analog value relative to the plural reference voltages. The intermediate signal is used to decrement the high voltage and increment the low voltage, so that the reference voltages produced by the voltage divider assume subrange values. The process is repeated for as many clock cycles as is required to converge the high and low voltages to equal the analog voltage.

Abstract: A classifying system for determining with which group of a plurality of groups of reference file words a data word most closely compares and comprising a plurality of groups of comparison means each constructed to simultaneously and individually compare a different group of file words with said data word to produce a comparison pulse for each comparison of said data word with a file word. Means are provided for identifying each group of file words in which the comparison of not more than one file word with the data word produces a comparison pulse whose amplitude exceeds, in a given direction of polarity, the predetermined amplitude of a threshold signal, and further for identifying each of said one file words.