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Hello All - As this matter has recently emerged as a thread, I have cleaned up my small application note on the topic and posted it to my web site. Application Note AN101 describes the background and recommended solution for the EPROM programming problem with the H50W mask set. It also includes a description and schematic of my Vpp power management circuit which attempts to avoid the application of Vpp to a device unless Vcc is present. You can find AN101 at http://www.smithmachineworks.com/embedprod.html Happy programming, Bob Smith --- Avoid computer viruses, Practice safe hex --- -- Specializing in small, cost effective embedded control systems -- Robert L. (Bob) Smith Smith Machine Works, Inc. 9900 Lumlay Road Richmond, VA 23236 804/745-1065

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