The Security Guard duty monitor below, shown in eight circuits at Digital Circuits – 1 are examples of logic circuits, i have converted them from the DOS Orcad to Orcad 9 and corrected some errors a few years back.
These circuits can be used for looking at the logic blocks or to learn. This product was built and sold to some firms many years back. Now these designs are best done with a PIC or Atmel chip. Here is the user manual Electronic Shift Monitor ESM9000