[Àû¿ë´ë»ó: 0.74_SVN_new, DOSBox-x]

If set, DOSBox will enable the A20 gate when Windows 3.1/9x broadcasts the INIT message
at startup.

Windows 3.1 appears to make assumptions at some key points on startup about A20 that don't quite hold up and cause Windows 3.1 to crash when you set A20 emulation to a20=mask as opposed to a20=fast.

This option is enabled by default.