8031-51 Second level board (Board "B")

8031-2,51,52 microprocessor.
27256 (32K) EPROM memory, address 0 - 7FFF (/PSEN).
6264 (8Kx8) RAM memory, address 0 - 1FFF (DATA).
1OUTPUT PORT (RS232C).
64 pin Bus expander.
I/O Decoder (data).
Clock Frequency: 12 MHz.
Single Power Supply (+5V).