Geoffrey Reed wrote: For NMOS EPROMs like the 2716 and 27128, the maximum Ipp spec was often somewhere around 30-50 mA. Of course, different vendor's parts had different specs. I haven't made a wide study of Ipp specs, so you'd have to check the datasheets for specific parts, but I suspect that few or none needed more than 100 mA. Bipolar PROMs, on the other hand, typically need a lot of current. The 82S129 needs up to 400 mA for Vccp, and up to 220 mA into the data output pins. Eric