On Oct 19, 18:10, Ian Primus wrote: program No, they don't, and if you try it, you may destroy them. They're high-speed (usually 35ns, but the suffix -35, -40, or -45 gives the actual number) 4k x 8 UV-erasable EPROMs, and to get the speed they use a different cell construction and a different programming technique. The bits in an erased device are "undefined" and whether you want a '1' or a '0' you have to program the actual value. Pinout is pretty much the same as a 2732 except that pin 20 is /CS1 instead of /OE, and pin 18 is CS2 (active high) instead of /CE. My ICT data book doesn't give the programming algorithm, which is obviously proprietary. It just says contact ICT or use a DATA I/O Model 29B with Unipak 2 or 2B firmware version V15. Oh, and like every other EPROM manufacturer I know, ICT say that exposing it to UV for longer than necessary will affect reliability, shorten the life, or in extreme cases, destroy the device, so don't expose them to a UV eraser (standard 12mW/sq.cm) for more than 20 minutes. Overnight is a bad idea! -- Pete Peter Turnbull Network Manager University of York