To use SdBC with Winboard add the following entries to winboard.ini:

"SdBC_0.5.15.0" /fd=Engines\SdBC\0.5.15.1 /fcp="sdbc.exe -C 32"
"SdBC_0.5.15.0" /sd=Engines\SdBC\0.5.15.1 /scp="sdbc.exe -C 32"

This assumes that you have stored SdBC in the path "Engines\SdBC\0.5.15.1".

To set the position cache size ( Hash ) for SdBC you need to 
add -C <size in MB> to the command line.
E.g. to let SdBC use 64 MB cache use "sdbc.exe -C 64".
Note the uppercase -C


