Shipping is combined with multiple purchases. 

Excess shipping costs will be refunded back to you.

Up for sale is National Semiconductor DM74S287N (256 x 4) 1024-BIT TTL PROM 20pcs in Original Tube. 

Mostly 1991 date codes. 

Possibly NOS (strongly believed to be) but unknown, untested and sold as-is.

Please see photo's for personal evaluation and specifics.