[Àû¿ë´ë»ó: 0.74_SVN_new, DOSBox-x]

A20 gate emulation mode.

The on/off/on_fake/off_fake options are intended for testing and debugging DOS development,

or to emulate obscure hardware, or to work around potential extended memory problems with DOS programs.

on_fake/off_fake are intended to test whether a program carries out a memory test to ensure the A20

gate is set as intended (as HIMEM.SYS does). If it goes by the gate bit alone, it WILL crash.

This parameter is also changeable from the builtin A20GATE command.

fast : Emulate A20 gating by remapping the first 64KB @ 1MB boundary (fast, mainline DOSBox behavior)

mask : Emulate A20 gating by masking memory I/O address (accurate)

off : Lock A20 gate off (Software/OS cannot enable A20)

on : Lock A20 gate on (Software/OS cannot disable A20)

off_fake : Lock A20 gate off but allow bit to toggle (hope your DOS game tests the HMA!)

on_fake : Lock A20 gate on but allow bit to toggle