you don't need to upgrade to PRO to have some a/d conversion. POKE and PEEK to AD converter do the job. see this link
http://www.melabs.com/resources/samples.htm#pbc choose adc71.bas. Should be enough to start a/d

i did a GOOGLE search and find this link

http://forums.basicmicro.net/ShowPos...stID=5245#5248

for sure there's many other...