On Oct 2, 20:38, Ram Meenakshisundaram wrote: [please don't post multipart :-)] = It's a standard 32768 x 8 CMOS EPROM, 70ns access time. I have the data sheet if you really need it. Pinout is: Vpp 1 28 Vdd A12 2 27 A14 A7 3 26 A13 A6 4 25 A8 A5 5 24 A9 A4 6 23 A11 A3 7 22 ~OE A2 8 21 A10 A1 9 20 ~CE A0 10 19 D7 D0 11 18 D6 D1 12 17 D5 D2 13 16 D4 GND 14 15 D3 Like many devices of its time, it has an electronic signature, though it's unlikely your circuit checks that. Anyway, the signature is obtained by applying normal read voltage to all pins, except you apply 12V to A9. Then with A0 at logic 1, you get the manufacturer code 0x98 and with A0=0 you get device code 0x45. -- Pete Peter Turnbull Dept. of Computer Science University of York