TL�F�6561DM74184�DM74185A BCD-to-Binary and Binary-to-BCD ConvertersJune 1989DM74184�DM74185ABCD-to-Binary and Binary-to-BCD ConvertersGeneral DescriptionThese monolithic converters are derived from the 256-bitread only memories� DM5488� and DM7488� Emitter con-nections are made to provide direct read-out of convertedcodes at outputs Y8 through Y1� as shown in the functiontables� These converters demonstrate the versatility of aread only memory in that an unlimited number of referencetables or conversion tables may be built into a system� Bothof these converters comprehend that the least significantbits (LSB) of the binary and BCD codes are logically equal�and in each case the LSB bypasses the converter as illus-trated in the typical applications� This means that a 6-bitconverter is produced in each case� Both devices are cas-cadable to N bits�An overriding enable input is provided on each converterwhich when taken high inhibits the function� causing all out-puts to go high� For this reason� and to minimize powerconsumption� unused outputs Y7 and Y8 of the 185A and all‘‘don’t care’’ conditions of the 184 are programmed high�The outputs are of the open-collector type�DM74184 BCD-TO-BINARY CONVERTERSThe 6-bit BCD-to-binary function of the DM74184 is analo-gous to the algorithm�a� Shift BCD number right one bit and examine each dec-ade� Subtract three from each 4-bit decade containing abinary value greater than seven�b� Shift right� examine� and correct after each shift until theleast significant decade contains a number smaller thaneight and all other converted decades contain zeros�In addition to BCD-to-binary conversion� the DM74184 isprogrammed to generate BCD 9’s complement or BCD 10’scompl...
