Vintage 100ns RAM chips, 256k x 1, page mode, DIP package. Made in the USA by Micron Technologies.
This part is a drop-in replacement for a variety of similar chips with different part numbers from various manufacturers. It will work as a TI TMS4256-10NL (or slower), and any number of the 41256-10 (or slower) chips and their equivalents.
Listing is for 4 ICs per lot.