Description
74185 – BCD-to-Binary and Binary-to-BCD Converters
General 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 comprehend 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.
The function performed by these 6-bit binary-to-BCD converters is analogous to the algorithm:
a. Examine the three most significant bits. If the sum is greater than four, add three and shift left one bit.
b. Examine each BCD decade. If the sum is greater than four, add three and shift left one bit.
c. Repeat step b until the least-significant binary bit is in the least-significant BCD location.
