#119 BIOS A20 gate support, int 15h, AH=24H

[Eric Larouche]

This patch implements BIOS support
for A20 gate in system call int 15h,
subfunction AH=24h.
Int 15/AX=2400h - DISABLE A20 GATE
Int 15/AX=2401h - ENABLE A20 GATE
Int 15/AX=2402h - GET A20 GATE STATUS
Int 15/AX=2403h - QUERY A20 GATE SUPPORT

Don't know if there would be an interest
to emulate the "fast gate" method? The keyboard
8042 method emulation is already there in DOSEMU.

[Stas Sergeev]

Thanks!

Its free software, so no one would
order you what to implement next, or
what not to implement.
Since we do that for our users, we
usually look into a bug tracker to
see what is to fix or implement, but
you are certainly free to do things
the way you like. :)