I pulled out a Commodore Datasette to see if I could get it working well enough to make physical C64 tapes from digital backups. The basic idea was simple: record a TAP file to cassette on a standalone deck, move that tape over to the Datasette, and load it on a Commodore 64. The first test showed the Datasette had power and did respond, but the C64 only produced garbled results and dropped back to READY instead of loading a program.
I went ahead and compared the Commodore unit to a more typical cassette recorder. The Datasette only connected through the Commodore plug, drew power from the computer, and handled the signal conversion internally, so there were fewer external controls to work with. For recording, I used TapDancer on a phone and fed the audio into a Pioneer tape deck, watching the VU meters and setting the levels around zero while recording a copy of Parallax.
With that first tape failing, I cleaned the Datasette head with IPA and cleaned the Commodore connections with DeoxIT. I also cleaned inside the Datasette connector using foam swabs so I could reach the contacts inside the shroud. That didn’t change the behavior, and recording onto the other side of the tape didn’t help either.
To remove the tape and recorder from the equation, I tried one of those cassette adapters with the cord coming out of the side and fed TapDancer straight into the Datasette from the phone. That still didn’t load anything useful, so I switched over to checking head alignment. I loaded a cassette azimuth program on the C64, adjusted the tiny screw through the access hole while watching the pattern on screen, and used that to dial in the head until the lines looked as clean as I could get them.
That got me a little farther. After the azimuth adjustment, I was able to get Parallax to start and even heard the loading audio, but it only loaded partway. I also had trouble with the Pioneer deck itself after changing its belts, because the transformer overheated and failed, so I replaced that recorder with a Sansui deck and made more test tapes. I even opened a sealed old stock cassette and tried fresh media, but I still couldn’t get a reliable load from a tape recorded on another machine.
At that point I checked whether the Datasette could at least save and load its own recording. I saved a small program from the C64 to tape with the Datasette, rewound it, and loaded it back successfully. Then I found the TapDancer inverse audio setting, turned that on, and finally got Parallax to be found and load much more convincingly. It still wasn’t stable enough to count as solved, and later attempts with physical tapes kept failing. I also noticed the recorder I was using had a stereo head while the Datasette used a mono head, so I tried another mono machine as well, but that didn’t fix it.
I opened the Datasette, found the belt a bit loose, and replaced it with a tighter one. After that, Donkey Kong loaded far enough to show the Ocean screen and music, but the game froze instead of running.
The Datasette ended the session partly working. It could save and reload its own data, it could read through the cassette adapter, and it got closer with a new belt, but I still couldn’t make a dependable physical reproduction tape load all the way through.
— Aaron
Links
- Minimal head alignment program
- Cassette adapter
- “Fakebit World”, “Flicker” by Malmen
- “MEGA” by Emil Rottmayer
Timestamps
00:00 – Intro
02:28 – First Look
06:00 – Here’s The Plan
08:00 – Initial Test
10:00 – Steps To Follow
12:10 – Cleaning
14:14 – More Tests
15:12 – Trying A Cassette Adaptor
16:58 – Checking the Azimuth
20:58 – A New Recorder
22:57 – A New Tape
23:53 – Self Test
25:15 – Inverse Audio
27:57 – Mono Heads
29:41 – Change The Belts
35:05 – Wrap Up