Do you have any device that will play the tapes now?
If so, what kind of output does it have?
Something with a RCA-plug (usually 1 red and 1 white) style line out would be best.
Then, run the analog signal through an analog to digital converter with a USB output.
A quick search on amazon has some:
Amazon.com: analog to usb digital converter
www.amazon.com
Again --
double-check any product in which you're interested to be sure that it has a USB output. I noticed that some have only digital-optical and SPDIF outputs. BE CAREFUL.
On the Mac, you might use the free app "Audacity" to record and edit the incoming signal.
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