Back Up Your Commodore 64 Cassettes with TrueTape64

Early home computers, mostly from the 8-bit era, used cheap cassette tapes for data storage. Computers like the Commodore 64, ZX Spectrum, and TRS-80 did not have any internal storage and floppy disks were not yet common among home users. The cassette tapes used for storage were the same as those used for music, but they contained bits and bytes stored as audio tones. Unfortunately, those tapes are susceptible to data corruption. That's why you should back up any old data cassettes that you can still access. Francesco Vannini's open source TrueTape64 device can help you with those backups.

The easiest way to back up a data cassette is to play it on a standard cassette tape player and record the audio output through a computer's soundcard. You can then process that audio recording to extract the data. But that method can be unreliable, because the processing is finicky. The TrueTape64 lets an authentic Commodore 1530 Datasette device handle the data extraction and then records the data that the Datasette thinks it is outputting to a Commodore 64. That means that TrueTape64 gives you the ability to dump data cassettes even if you don't have a working Commodore 64. All you need is the TrueTape64 and a Commodore 1530 Datasette. You can then use a Commodore 64 emulator to read the backups.

The Commodore 1530 Datasette device doesn't actually send digital bits to the Commodore 64. Instead, it uses custom circuitry to reliably detect the soundwaves on the data cassette and tells the Commodore 64 the exact timing of the pulses via the CIA (Complex Interface Adapter) chip. The TrueTape64 replaces the Commodore 64's CIA chip and reads the pulse timing. It sends that data to a modern computer over USB, so that computer can store the data and process it into a usable backup. Because the Datasette's dedicated circuitry is doing the heavy lifting of processing the audio, the resulting data should have fewer errors.

The TrueTape64 device is affordable to build and it only requires a handful of common components. Those include a Microchip ATtiny2313-20PU microcontroller, a 16MHz crystal, a DC-DC voltage booster, an FTDI232 serial-to-USB adapter, some resistors and capacitors, and a handful of connectors. After assembling the device and uploading the custom firmware to the microcontroller, you can use the provided Python CLI (Command Line Interface) tool to collect the data and write it to a standard TAP file.