Problems Booting PowerMax

V86 mode detected error

V86 mode detected error

The CPU in the computer has several modes of operation. V86 mode (or Virtual 8086 mode) allows older code (written for real mode) to work in a protected mode environment. When the computer starts up it's in real mode, so the OS expects to start in real mode without any prior protected mode restrictions.

The problem with real mode is that software can only use around 640Kb of memory, regardless of how much is installed. DOS is a real mode operating system and can't access all the memory by itself so often a memory manager is installed to make the rest of memory available. To do this the memory manager normally switches the CPU into protected mode and runs DOS as a V86 mode task.

If the CPU is in protected mode (and DOS is running as a V86 task) the setup code for PowerMax doesn't have complete access to the computer and can't boot.

This is a problem inherent in booting from DOS. It can be worked around depending on the memory manager installed. EMM386 (the memory manager supplied by MicroSoft) is a popular memory manager. If it's installed you will need to disable it just before starting PowerMax (so you don['t get an error mesage). This is done by typing "emm386 off" at the DOS prompt.

Other memory managers are likely to have similar abilities, see the documentation that came with the memory manager for details. If the memory manager can't be disabled you can still boot PowerMax from DOS if you skip or remove the memory manager from CONFIG.SYS.

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Copyright 1998, Brendan Trotter