<> Memory says 82s129, I have the data sheet home in that 1971 signetics <> data book. I was my first ttl databook! < <The 82S129 was a fusible-link PROM. It was an actual device, and in <production until quite recently. And old... I had my data sheet out when I typed that... can you say transient ischemic attack {blonde moment}. I could, if I remember. <Incidentally the nominal Vff is given as 6.3V. I wonder how many <modern-day engineers would realise the significance. that's 6.3V AC, after all it is an indirectly heated cathode. ;) Don't forget the drain [as in spigot] or the bit bucket under it. <If anyone wants to get this data sheet, it's reprinted on page 605 of the <'Student Manual for the Art of Electronics' by Thomas C Hayes and Paul <Horowitz (2nd Edition, ISBN 0-521-37709-9) I consider that a classic, both the book and the data sheet. Allison