Norpak was a logic device that used only 'NOR' gates. It preceded the PLC concept. The gates were hardwired. Since any logic function can be created using negative Boolean operators (NOR or NAND) they were usable for solid state control systems in place of relays. We used a Norpak system at the San Francisco International Airport on a plane fueling system in the middle 1960s. They had 10 NOR gates per module, and we wired modules using something like #20 AWG wires with some kind of termination on the end that could be inserted into the Norpak units. One had to be very careful using the units because after the various functions and their arrangement had been designed there were often redundant gates in series that could be eliminated, but this caused transparency of design to be lost. I was working for the Standard Oil Company of California in those days down on 225 Bush Street. Reid C. Allen, P.E. Roberts & Schaefer 10150 South Centennial Parkway #400 Sandy, Utah 84070 Reid.Allen at eni.com Tel: 801.984.0900 Ext. 210 Fax: 801.984.0909 Cell: 801.634.5640 NOTICE: This e-mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution, copying, or other use of this message or its attachments is strictly prohibited. If you have received this message in error, please notify the sender immediately by replying to this message and please delete it from your computer.