Another issue with 74C922......presuming that they are not an end of life product (which I do not know).....I checked 3 different online sales sites and see that the low quantity price for these are over $6 US. That seems like it may cost nearly what a whole 8051 can cost. Could this be the reason that almost all designs that I have seem in recent years use direct software scanning of a keybad by putting it right on the port pins of the processor?
Michael