Composes a 16-to-1 multiplexer using 74151/74HC151/74HCT151 for the purpose of creating an active low signal when the selected status condition flag is also low.

See also project resources:

• https://github.com/Johnlon/spam-1
• https://hackaday.io/project/166922-spam-1-8-bit-cpu
• https://www.youtube.com/channel/UCG6rvUou0GMLyTbjs4Ro2zg