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How MS-DOS Engineers Cracked the 640 KB Barrier: HIMEM.SYS, EMM386.EXE, and the Art of Loading High
A practical walkthrough of how MS-DOS 6.22 used HIMEM.SYS and EMM386.EXE to break the 640 KB barrier — covering the HMA, UMBs, EMS vs XMS, a real CONFIG.SYS example, and the compatibility trade-offs that still matter for legacy systems.
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