10-LINE-TO-4-LINE AND 8-LINE-TO-3-LINE PRIORITY ENCODERS

The SN54/74LS147 and the SN54/74LS148 are Priority Encoders. They provide priority decoding of the inputs to ensure that only the highest order dataline is encoded.Both devices have data inputs and outputs which are active at the low logic level.
TheLS147 encodes nine data lines to four-line (8-4-2-1) BCD. The implied decimalzero condition does not require an input condition because zero is encoded when all nine data lines are at a high logic level.
TheLS148 encodes eight data lines to three-line (4-2-1)binary (octal). By providingcascading circuitry (Enable Input EI and Enable Output EO) octal expansion is allowed without needing external circuitry.