> that stays inside the 640K barrier Yes, but to be super pedantic, it stayed within the 1MB barrier[1] that real mode could "officially" address. It was perfe

> that stays inside the 640K barrier Yes, but to be super pedantic, it stayed within the 1MB barrier[1] that real mode could "officially" address. It was perfectly okay to have your EMS window above the A000h segment in memory, i.e. above 640k, if no device was using it. [1] Plus some change known as the "high memory area" (HMA), an artifact of how linear addresses are calculated from segment and offset.