Your posting is in the wrong category.
"About the board..." means about the
Bulletin Board not about a mainboard of a Proteus 2000... (-> Everything Else)
The 72-way SIMM socket is available at
http://www.rs-online.comManufacturer: Winslow AdaptICs
Model #: WS3172SMRRC (rightpolarised) or WS3172SMLRC (leftpolarised)
Search for the model numbers then you will find the SIMM sockets.