I use the Radio Shack CCR-81 (Computer Cassette Recorder). The key to this series of tape recorders from Radio Shack, was that they had an Automatic Level Control on them for the Line Input connection (although they didn't really advertise this in their literature). Since the signal from the M100 is rather high (<1 V pp) the recorder needs an ALC circuit to prevent over driving the Line Input connection and distorting the recording. Otherwise the recorder is not different than what was common for audio recordings at the time.
An interface cable can easily be built from still commonly available parts (unfortunately no Radio Shack stores anymore), or the original type shows up on eBay occasionally. Regards, Peter
