California Computer Systems - 2065A   64K Dynamic RAM Board
CCS made two 64K Dynamic RAM boards. This was their first one.

CCS's 2065A 64K Dynamic Ram board provided S-100 systems with 64K of reliable, high-speed dynamic RAM. Compatible with most of the major S-100 systems on the market at the time, including those with front panels, it supported DMA operations and required no Wait states with up to 4MHz  microprocessors. The 2065  was designed for memory expansion; it allowed you to  expand your memory up to 512K.  
 
Through  the  bank  select system, you could hardware-assign your board to any level or combination of levels of 64K and then software-select the bank you wish to work with. When the board's bank was selected, the Bank LED lit. The 2065's bank select system was compatible with the bank select systems used by Cromemco, North Star, and others. In addition, the 2065 give you flexible memory. Any 16K memory block could be completely disabled or can be made independent of the bank select system, allowing it to be enabled any time it is addressed, regardless of which bank was selected.
 
All 64K could also be enabled every time you turn on or reset your system, without the board's bank being software-selected first. When an enabled 16K block was addressed, the Board LED is lit. The 2065 give fairly reliable memory. Its dynamic memory refresh circuitry provided processor-transparent refreshes during normal operations with a Z-80 or 8080 CPU. It also provided for memory refresh during DMA and extended Wait states when normal refresh generation was inhibited.