The CPU board may be fitted with either 2MB of Data Memory RAM using 256Kbit devices, or either 4Mb or 8MB using 1Mbit devices. To accommodate these different sizes of Data Memory, two jumper areas are used. The MSB jumper (near I3J3) selects the Most Significant Bit for RAM Bank enable. The OVF (near I3I5) jumper selects the overflowed address bit and is used to generate the address wraparound error. The jumpers are set as follows:
