The first 555 timers, the NE555V/SE555T from Signetics ... The comparators have a propagation delay of only 3.5 ns, with the NOR gates typically under 2 ns and offering some of the fastest ...
Basically, it’s a 555 with a huge programmable capacitor ... greatly increasing the time delay of the chip’s stock configuration. It’s a neat build, and an awesome introduction to a ...