How can I convert a 4-digit BCD number to Binary in hardware? (using 74LS ICs and GAL22V10 ICs)
Since you appear to be happy to user older technology, you could use a 16-bit xPROM (Flash EPROM or EEPROM if you prefer). Feed the BCD into the address lines and take the result from the bottom 10 bits of the data lines. The hex-file to program the PROM is left as an exercise for the reader.