PIO-6834-2/4M-1 is a 2MB or 4MB I/O slot memory expansion board manufactured and sold from 1990 by I.O Data for X68000 which have or have been expanded to 2MB.
The main memory needs to be configured as one continuous block and you can configure the board to start addressing main memory from the following locations:
MB | 1 | 2 | 3 | 4 |
2M | OFF | OFF | OFF | OFF |
4M | ON | OFF | OFF | OFF |
6M | OFF | ON | OFF | OFF |
8M | OFF | OFF | ON | OFF |
10M | OFF | OFF | OFF | ON |
The default settings are 2MB