Cleaning out the garage to set up my photo studio and I ran across boxes of Commodore 64 gear given to me by a friend for my birthday a couple years ago. Among the items: some crusty old cassette tapes with data on them. Back in the day, disk drives were expensive luxury items for saving your data (and the disks were costly too). The cheaper alternative: a “datasette” – a specialized tape recorder that can save and load to standard and widely available audio tapes. There were some quirks to working with tapes: they are extremely slow, must be manually positioned at the right point, and like all magnetic media the tapes “should be” carefully stored.
Fortunately retrocomputing hobbyists have since worked out long-term digital storage solutions for the analog data on the tape of various 8-bit computers. On Commodore machines this is the TAP file – a digital representation of the various pulse lengths detected on a tape. It can be replayed in an emulator, or turned back into a pristine WAV file to be used in a real machine (record it back to a new tape, etc).
Now, the ‘preferred’ way to dump a tape is to use a special cable to link the C64 to your PC, but I only have three tapes here and there’s no way I would go to the effort of that. Instead I settled on the super cheap method: hook a standard tape deck to the line in of the computer sound card, record the WAV, then use a tool to make a TAP file out of it. Not a very good solution for people with a lot of tapes to dump, because the resulting file needs a lot of manual cleaning to work properly afterwards. The tool suite I used to fix it all up were:
- Audacity to record the wave. Use 96khz sample rate if your hardware supports it.
- UberCassette (or an alternative, e.g. AudioTap) to turn a wave into a .tap file
- tapclean to clean up, standardize, repair and verify the tap image
- a hex editor to do a good bit of manual cleanup
- A good reference on the tap file format!
End result of all this: I managed to fully dump the three tapes that I own. One is “Dungeons of Death” for the VIC-20, a previously unreleased RPG. Another is “Touch Typing Tutor” for C64: a .prg file existed, but no tape dump or scans. And the last… a tape with programs that my friend had written back in 1985 or so. Now that I’ve gotten the hang of this, I’m out of material! So there’s an open request out for C64 tapes. If you’ve got them, I may be able to dump them.