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Tutorial : How to dump an old Atari cassette/tape to a CAS or WAV file


Marsupilami
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Hi folks,

 

Since some of you found this post usefull on my website, i've improved visibility : It's now here : https://atarinside.dyndns.org/blog/index.php/tutorial-how-to-dump-an-old-atari-cassettetape-to-a-cas-or-wav-file/

 

It's also the 1st birthday of atarinside and the 100th software release, thanks for your loyalty ! :)

 

post-21529-0-82850100-1503744836.jpg

 

Best Regards,

 

Marsupilami.

 

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Missing requirement: the tape recorder, cable, and input must be stereo for most tapes. This is important to note since most other computers did not use stereo tape and this is necessary even if there is no audio track, due to noise. It is easy to forget to check whether the tape recording actually has a stereo output.

 

Microphone input is not recommended because it is usually mono and often will give you distortion, especially if the +20dB boost option is enabled (default). Line In is preferable.

 

0.5 on Audacity's waveform graph isn't 0.5dB, it's half amplitude. Half amplitude is -6dB, max is 0dB. While adjusting the volume level is a good idea, it is not critical for recovering the data -- they can be decoded at much lower volume levels than that. Also, if it's a tape worth saving, don't delete a recording that is too loud or too soft until you're sure you don't need it; it may still be recoverable even if it sounds awful.

 

The carrier and data ideally should not have that big of a difference in volume. This is usually a sign that the tape recorder is applying noise reduction to the tape audio, which is not desirable for data. At 600 baud this won't really be a problem, but it is best to disable any noise reduction on the recorder like Dolby B if it has buttons to do so. Doing so is much more critical for turbo encoded tapes.

 

I would note not to trim the leader at the beginning, even the part before the carrier. This is a common mistake. The OS cassette tape routines unconditionally wait for 15 seconds of leader to pass before even trying to read from the tape, so if too much of the leader is removed, the OS will miss the beginning of the data.

 

CLOAD only works if the tape contains a BASIC program. If it is a binary bootable loader, then it will need to be booted via holding the Start button, and the auto-boot option in the emulator will need to be adjusted accordingly.

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One writes a tutorial and people are swarming immediately :)... with good suggestions.I believe Phaeron's notes are worth incorporating in the tutorial.

 

The "stereo problem" and "microphone problem" are common pitfalls worth mentioning. It is a price to pay for the otherwise good idea of dual track. Switching off Mr. Dolby is also good point. In general, it is good to switch off all features that change the signal - DOLBY, DBB, X-BASS, 3D sound, equalizer, or whatever. Some advanced stereos have those. Good for music, bad for our precious data tracks.

 

On one hand, it is regrettable the laptops have only MIC IN, on the other hand, music is nowadays distributed mostly in digital form, so why equip laptops with LINE-IN when advanced users can always bring more cash and buy an external sound card (inside of a PC is full of noise anyway).

 

As for adjusting of the volume level, for standard FSK tape records, the volume does not matter that much (unless the signal is too weak and hard to distinguish from noise).

When sampling a new recording with opportunity to adjust the volume, it is good to do it. With turbo tapes (PWM based), my experience indicates that it is almost a necessity. Just follow the rule - as much close to the red area as possible, but not in the red area ;-)

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