The DM and DMB series of boards were quite similar. The DM did not have bank
select capability, the DMB did.
The board consisted of 64K of dynamic RAM with refreshing independent of bus
timing. No wait states were required wit a 4MHZ Z80. The board was
addressable in 4K increments at 4K boundaries. The board utilized low
power, fully loaded it used less than 8 watts.
This board had bank selection (Cromemco & Northstar format). One of 256
ports could be selected (40H for Cromemco, C0H for Northstar). Up to 8
boards could be used per port. Each 16K or RAM could be set to start
at 0000H, 4000H, 8000H, or C000H for any of the banks selected by the port.
The bank memory size could be incremented from 16K to 64K in 16K increments
allowing 512K bank sizes.
The manual for this board can be obtained
here, the schematic
here, and updates
here and
here.
