It looks like mc1502 uses same cassette format as ibm5150 (and probably the same BIOS code):

[Linked Image from img-fotki.yandex.ru]

Tape dumps are at http://www.pk-info.ru/ms1502/files/ but 3 of 4 are corrupted (truncated?). "Tape13" is OK, and is the one in the screenshot.

Cassette input in mc1502 itself doesn't yet work.