FOUND 1-1 replacement for Ambicom WL1100C-CF/Yamaha wireless 802.11b CF card ==> DLink DCF-660W
So my PRC-100 has landed on the floor a number of times, and several weeks ago, it landed on the floor one too many times. It would no longer connect with my Mark IV! :(
I thought maybe it just reset - so I tried various things to get it to re-pair with the piano - nothing worked. Finally, I figured I'd diagnose if my wireless card had gone bad. If you go into the Qtopia menu on the bottom left - and click on Settings, Network - you should be able to see Services. You can try pairing your device with a 802.11b network (say your own wireless router, or guest network). You can manually change the ESS-ID to either your guest network or your Piano's network's name (My Piano is DKV221XXX). If your wireless card is working, when you click on the Current tab - you should see a connection along with Signal and Quality % bars. If not, your wireless card may be bad.
Mine did not have any readings. So what I did was I turned off my Piano, and popped out it's Ambicom card out - and plugged it into my PRC-100. I found that right away my PRC-100 could see my guest network - so I had narrowed it down to the card.
I went onto eBay to try to find an Ambicom WL1100C-CF - unfortunately, there seems to be one seller that has a lock on all these used CF cards (PCMONDE) and is selling them for about $70-80! If you're lucky you can find a working used one for around $10-25. I figured that there must have been a number of equivalent units that used the same chipset during that time frame, so I started searching to see if there were any 802.11b cards that were compatible with the Sharp Zaurus SL-5500 (essentially our PRC-100 is a rebadged one). I found that the Ambicom ises a Prism 2.5 chipset - so I searched for compatible device lists...and found that the Dlink DCF 660W was on the list. Bought one off of eBay...and just confirmed that it works without any tinkering! My PRC-100 is now as good as new.
http://www.amazon.com/D-Link-DCF-660W-Network-CompactFlash/dp/B0009M08XS/
So we have another viable replacement alternative for this part. Hope this helps someone!
Vincent