Digital Research Computers -- 128K RAM/EPROM Board  III
This was a useful ROM board in that it could take RAM or ROM together on the same board.  It may be the last S-100 board DRC made.

I used this board to hold my version of the IBM PC BIOS. It used the popular 28 pin 2764 style 8K x 8  RAM/ROM chips. Each chip location could be disabled. It  met all the IEEE-696 specifications and so had 24 bit addressing as well as 8 or 16 bit data paths.  You could add up to 7 wait states. You could set it to byte low or byte high mode for even/odd  addresses.   It did support the S-100 bus Phantom line for input but unfortunately not output (to inactivate othere overlapping RAM on the bus). 

The (short but adequate) manual for this board can be obtained here.