74184 Datasheet | National Semiconductor

Description These monolithic converters are derived from the 256-bit read only memories DM5488 and DM7488 Emitter connections are made to provide direct read-out of converted codes at outputs Y8 through Y1 as shown in the function tables These converters demonstrate the versatility of a read only memory in that an unlimited number of reference tables or conversion tables may be built into a system Both of these converters prehend that the least significant bits (LSB) of the binary and BCD codes are logically equal and in each case the LSB bypasses the converter as illustrated in the typical applications This means that a 6-bit converter is produced in each case Both devices are cascadable to N bits An overriding enable input is provided on each converter which when taken high inhibits the function causing all outputs to go high For this reason and to minimize power consumption 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 CONVERTERS The 6-bit BCD-to-binary function of the DM74184 is analogous to the algorithm a Shift BCD number right one bit and examine each decade Subtract three from each 4-bit decade containing a binary value greater than seven b Shift right examine and correct after each shift until the least significant decade contains a number smaller than eight and all other converted decades contain zeros In addition to BCD-to-binary conversion the DM74184 is programmed to generate BCD 9’s plement or BCD 10’s plement Again in each case one bit of the plement code is logically equal to one of the BCD bits therefore these plements can be produced on three lines As outputs Y6 Y7 and Y8 are not required in the BCD-to-binary conversion they are utilized to provide these plement codes as specified in the function table when the devices are connected as shown DM74185A BINARY-TO-BCD CONVERTERS The function performed by these 6-bit binary-to-BCD...