The 8KRA Static Read/Write Memory Module had a capacity of 8K and operated in a static mode.  This was an early non-IEEE 696 S-100 RAM board.   As opposed to dynamic memories, the 8KRA needed only one power supply and did not require periodic refreshing.
 
All address and data lines were fully buffered, and extensive noise immunity circuitry was built into the memory. The board fea­tured a switch selectable address selection which allowed its starting address to be offset in 1K increments from zero to 65K.
Maximum worst case access time for the 8KRA was 520 nsec. Thus, in any 8080 system, its memory would operate at the same speed as any other memory with an access time between 50 and 520 nsec. Both the access time and non-refresh features of the 8KRA meant no computer "waiting" time was required.
 
The 8KRA Memory was plug-in compatible with the Altair 8800 bus.  It required +7.5 to +10 V dc at 1.9 amp (max.) for its operating power. In addition, the low power memory IC's used on the module could operate in a low power (+1.6 to 2.5 V dc at 0.9 amp max.) standby mode. Data loss from the 8KRA during loss-of-power or power interrupt conditions could consequently be prevented by using two "D" size batteries for standby power.     Provisions for easily adding this standby capability were incorporated in the module design.

The manual for this board can be obtained here.