Counter Without Counter

48 EE March 1989 DESIGN IDEAS The contents of this column are based solely on information supplied by the author and do not imply practical experience by Elektor Electronics. COUNTER WITHOUT COUNTER Under this paradoxical title we present a design idea for a versatile counter concept that uses an EPROM instead of the expected counter chip. The circuit described here can be con- figured as an up- or down-counter from 0 to 99 in BCD or 8-bit binary mode, with reset, preset and enable inputs available. All control inputs are digital compatible, allowing the user to define his own control hierarchy. Moreover, the control inputs may be active high or ac- tive low. The counter is actuated by the positive transitions in the clock signal, and handles input frequencies well into the by N. Korber 5V 5V IC 1 EPROM 2764 0E3"1.23E8 19 MHz-range. All inputs and outputs are 14 remarkable because its features and ver- satility are achieved with only a handful of commonly available components. The...