Category Archives: x86

DOS Memory, Managers & Extenders, Part I

To understand why the maddeningly complex world of DOS memory managers and extenders came to be, it’s necessary to understand the evolution of the PC platform. Even though memory managers and DOS extenders reached their peak on 32-bit 386 and … Continue reading

Posted in DOS, PC architecture, PC history, x86 | 26 Comments

HIMEM.SYS, unreal mode, and LOADALL

The previous post talked about real mode on 286+ processors which behaves more like a slightly modified variant of protected mode rather than the old 8088/8086 processors. Real mode with non-compatible selector bases or limits is usually called unreal mode … Continue reading

Posted in DOS, x86 | 2 Comments

Will the real Real Mode please stand up?

Every programmer familiar with the x86 architecture understands the difference between real and protected address mode of the processor. It is well known that the real mode is compatible with Intel’s old 16-bit 8088/8086 CPUs, while protected mode was a … Continue reading

Posted in x86 | 3 Comments