Originally Posted by http://perso.numericable.fr/ckckck/C64.html
How to transfer a C64 tape on a PC ?
First plug a tape player on your PC sound input and record the whole tape. I sampled the tape with high volume, near to saturation. Same your sound to a MONO WAV PCM file. Then use "wavprg" program to extract PRG from tape raw file. If wavprg complain for errors, try to filter the wav file. I used CoolEdit to remove noises. WavPrg was ok for the first tape, but not the 6 next. In fact only a small boot program was found on the tapes. That boot program load data directly from tape. This can not be extract as PRG file (maybe yes, but I do not how). So I try another software : "wav2tap" This one convert a full raw tape into a full raw tap format called ".tap". This is supported by VICE (and PSPVice of course ) This way I extracted all the 12 tapes sides of my tapes.
And here's the util to do it: http://wav-prg.sourceforge.net/
Best of luck !!