The 74LS28PC: It performs the standard NOR logic function — output goes low when any input is high — and is used in general-purpose digital logic, glue logic, and control signal inversion in industrial and commercial equipment.
Sourcing and lifecycle
The 74LS28PC is listed as active in production, so there is no end-of-life or last-time-buy pressure on this line item. For a part this mature, the independent channel is the normal route — franchised distributors may carry limited depth, but the part is readily available through the surplus and excess market.