as shown in photos, erase and use.  I no longer have a PROM burner, so could not test.  very early UVPROM.  you are buying individual memory chips. Advanced Micro Devices Memory IC- 2 are AM2764-20DC made in Malaysia, one is AM2764-DC, country not marked. Status: Discontinued 2048 x 8 Erasable ROM.  Package: 24 Pin CDIP with window (Hermetic Dip) You are buying one at a time, please choose the quantity you want from the drop down list