Binary or BCD conversion circuit

Systems that need to perform arithmetic operations on data generally use binary form. To display these results, the data must be converted to BCD format. On the other hand, the address selection information from the digital switch must be converted to binary format before it can be used for memory addressing operations.

For applications that do not require fast conversion, a circuit that can perform both conversions is sufficient. Figure 1 shows such a circuit, which uses an up/down counter to obtain the desired result. When doing a binary/BCD conversion, the binary counter is preset with the binary value and the BCD counter is cleared. The binary counter counts down while the BCD counts up, and when the binary counter reaches zero, the BCD counter holds. For a BCD/binary conversion, the BCD counter counts down from the BCD value while the binary counter counts up.

Figure 1. Independent binary and BCD up/down counters can perform both binary/BCD and BCD/binary conversions in one circuit.