Vector Graphic 64K Dynamic RAM
This was Vector Graphics workhorse RAM board for all their later systems.

The Vector Graphic 64K Dynamic Memory Board provided up to 65,536 (64K) 8-bit bytes of random access memory. It could be used in most S-100 bus computer using a Z-80 CPU board. (Minor modifications may be necessary if system was not shipped with this board). It was an extension of their 48K RAM card.
  
The board had output buffer disable compatible with the Vector Graphic ZCB Board, which activates the  phantom in response to POC  and Reset. However DMA cycles not interrupt CPU for longer than 2X10^-3 seconds without generating the necessary refresh signals. The board had jumpers to disable either one or both of the two top RAM portions   (C0O0H to DFFFH and EOOOH to FFFFH). There was a switch selectable bank number assigned to each 64K board in a system.   The system selects a board by outputting a byte via port 40H to the appropriate bank. For simple 64K systems the bank is bank 0. In that state,  it is automatically selected when computer is first turned on or the RESET button is depressed.    If the board does not work first check it is setup for bank 0.
 
The schematic for this board can be seen here.
The manual for the board can be obtained here.