Kaypro Motherboard Add-On Question

[Jim Brain]

http://www.ebay.com/itm/USED-KAYPRO-4-COMPUTER-MOTHERBOARD-/331730690952?
The non soldermask boad on top of the main unit intrigues me.  Does 
anyone know what it is?

Jim

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Jim Brain
br...@jbrain.com
www.jbrain.com