The National Semiconductor SC/MP, developed around 1975, is an example of an engineering development system using a microprocessor. Though it is not a personal computer, a large number of enthusiasts built hobby computers adapted from kits like this which were inteded for industrial prototyping. This is the mother board for a development system- a do-it- yourself kit. A student/experimenter/etc. can customize cards to plug into the mother board to make a complete system. The long black connectors on the left are buses to plug cards into. A keyboard is used for simple programming and a small display above the keyboard. The chip with glass window is probably an EPROM. You can burn a program into the EPROM. The glass window is so you can erase the EPROM with ultraviolet light. +5 VDC, -12 VDC suppies tied to tied to ground for static protection. -- DS 3/18/99. Attached to the unit is a tag with directions how to apply power.