The first computer I owned was a VIC-20. I paid $600 for the base unit plus the Datasette. (This was a couple years before Canadian Tire was selling them for $50.) I spent many, many hours programming in BASIC and in 6502. I didn't have the luxury of a monitor program, so I would write out the program on paper, convert the mnemonics to hex opcodes, convert the hex to decimal and poke the program into memory. Yes, those were the days.
In the last couple of years, I've become more and more worried about the longevity of all my VIC tapes. I'd really hate to lose all the work I did. (Ya, I know it's not really worth anything now, but still... it was a labour of love.) I've thought alot about transferring these tapes to a modern, (more reliable?) medium such as CD-R. Also, with the development of VICE, the Versatile Commodore Emulator, it might actually be useful to transfer some of my old stuff.
I finally ran across the necessary information to write a program to decode these waveforms. The result is viccas - a program to convert wave files of commodore cassettes into .t64 files common in commodore emulators.
This program is far from polished. It is also far from finished. It does, however, work for me. I've used it to start transferring my old VIC cassettes to my PC. I hope it works for you also.
viccas is commandline driven. The syntax is simply "viccas wavefile.wav". It will name the output file based on the name of the vic file found in the header on the tape. It will accept basically any uncompressed PCM wave file, although I recommend 44.1khz, 8bit, mono. (It downconverts 16bit to 8bit internally anyway, so there's no advantage to using 16 bit.)
I hope you find this program useful. If you want to fix problems with it, please do, and please send me the fixes. Particularly, if you want to make it 64bit safe, and big/small endian safe, I would appreciate it.
Download the source for V0.3 Also contains WIN32 binary which requires the cygwin DLL available at cygwin.com