FYI:
For those with a CTK-900 or WK-3200 or WK-3700
to find this software to download, go to archive.org and in the wayback machine "enter URL or keywords" search box,
paste the full URL below into that search box (do nor click link below, just right-click and select highlight it and ctri-c (copy) it,
then paste into the wayback search box, then press [enter] to search
http://music.casio.com/e/data_ex3/before.html#software
The wayback machine should return all the dates it archived that URL, and then click on an entry in the 2005/2006 timeframe and you should get the old download
page where wk3-30.exe and also the manual can be downloaded from.
Best,
Scott / taybrynn