All information on this page was taken from: http://www.geocities.co.jp/SiliconValley-SanJose/6808/
XSIMM6 (Six Sim X) was invented and manufactured in 1994 by Systems Research Ltd., Tokyo. It is a memory expansion board with built-in SIMM memory socket and there are two variants of it:
This is due to different shape and mounting positions of internal memory expansion for XVI and XVI Compact.
These XSIMM boards use the following 72pin SIMM memory modules which height must not exceed 30 mm (the default height is 25 mm).
It supports 4MB and 8MB SIMM's (70ns and 60ns SIMM's will work but only at 70ns). It can expand the X68000 memory with additional 2MB, 4MB or 6MB. There is a dip-switch panel in the middle of the board right below the SIMM socket. The dip-switch settings are as follows:
The memory will be expanded with additional 6MB even if an 8MB SIMM will be installed and all four switches are set to ON.