I'm not sure about Macs, but PC-DOS/MS-DOS came with BASIC/BASICA[1] or GWBASIC[2] (or QBASIC[3] in the 90s with MS-DOS 5.0). I wrote a bunch of little fun programs when I was 12-13 in the BASIC that came with DOS.
[1] http://en.wikipedia.org/wiki/IBM_BASICA [2] http://en.wikipedia.org/wiki/GW-BASIC [3] http://en.wikipedia.org/wiki/QBasic