Actually, to a programmer the APIs, both the CP API and the PM API, were not very similar. Somewhat is a fairer assessment. They shared a common ancestry, and

Actually, to a programmer the APIs, both the CP API and the PM API, were not very similar. Somewhat is a fairer assessment. They shared a common ancestry, and some common ideas (such as the idea of sharing modes for open file handles, for starters), but they were in some respects markedly dissimilar to those of DOS+Windows.