Reconstructing BASIC from a cassette
Thrax
🐌Austin, TX Icrontian
Through the flurry of hardware releases, architecture and roadmaps, we occasionally stumble upon a delightful morsel of raw ingenuity that does nothing less than astound. Today, that morsel comes to us in the innocuous form of the Apple I BASIC cassette tape.
These cassettes are extremely rare, given that there were only 200 Apple I computers released, and less than 100 are known to exist. To make matters worse, not all Apple I computers came with this prized cassette tape. This tape contains the first piece of software that Apple ever sold.
In 2002 someone produced an audio recording of the BASIC tape being played back. A simple algorithm was created to analyze the waveform on the Atari, convert that to binary and run it on an Apple I emulator. They dumped the output of the emulated BASIC and released it to the public, where others continued to modify the code to correct what were perceived as errors. The only dump of the tape that can be easily found includes these changes, which gives us cause to question the accuracy of the code.
Assembly language blog Pagetable recently took another stab at the project by analyzing the original and unmodified WAV recording with new tools. With Audacity, custom conversion code and a HEX editor, Pagetable has produced the world's first certifiably pristine code of software that was written to magnetic tape more than 30 years ago.
What a fantastic and outrageously clever project.
These cassettes are extremely rare, given that there were only 200 Apple I computers released, and less than 100 are known to exist. To make matters worse, not all Apple I computers came with this prized cassette tape. This tape contains the first piece of software that Apple ever sold.
In 2002 someone produced an audio recording of the BASIC tape being played back. A simple algorithm was created to analyze the waveform on the Atari, convert that to binary and run it on an Apple I emulator. They dumped the output of the emulated BASIC and released it to the public, where others continued to modify the code to correct what were perceived as errors. The only dump of the tape that can be easily found includes these changes, which gives us cause to question the accuracy of the code.
Assembly language blog Pagetable recently took another stab at the project by analyzing the original and unmodified WAV recording with new tools. With Audacity, custom conversion code and a HEX editor, Pagetable has produced the world's first certifiably pristine code of software that was written to magnetic tape more than 30 years ago.
What a fantastic and outrageously clever project.
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