IBM's PC DOS (also marketed as MS-DOS by Microsoft) inherited the convention by virtue of being loosely based on CP/M, and Windows in turn inherited it from MS-DOS.
ˌaɪbˌiːˈɛmz pˌiːsˈiː dˌiːˌoʊˈɛs ˈɔːlsoʊ mˈɑːɹkɪɾᵻd æz ˌɛmˈɛsdˌiːˌoʊˈɛs baɪ mˈaɪkɹəsˌɑːft ɪnhˈɛɹɪɾᵻd ðə kənvˈɛnʃən baɪ vˈɜːtʃuː ʌv bˌiːɪŋ lˈuːsli bˈeɪst ˌɔn sˌiːpˈiː slˈæʃ ˈɛm, ænd wˈɪndoʊz ɪn tˈɜːn ɪnhˈɛɹɪɾᵻd ɪt fɹʌm ˌɛmˈɛsdˌiːˌoʊˈɛs.