Fun anecdote... the 7447 is a BCD to 7seg decoder not a binary/hex to 7seg, so no A thru F output when A thru F are input. There are super expensive options li

Fun anecdote... the 7447 is a BCD to 7seg decoder not a binary/hex to 7seg, so no A thru F output when A thru F are input. There are super expensive options like TIL311 and weird unobtanium that no on has ever heard of. But you can use a PIC in a tight loop checking the 4 inputs, lookup a byte in a 16 byte table, and squirt out 7 bits of LED that display nice A thru F along with the digits. It'll be enormously slower than TTL so you can't build latches that way but works fine for a nice slow asynchronous UI like a LED decoder / driver. This has been redone a zillion times online. Its a good "first microcontroller project". There is at least one ancient 12 or 16 series PIC thats pin compatible with a 7447 with the proper programming although its been 20 years.