<s>
DJ	B-Application
's	I-Application
GNU	I-Application
Programming	I-Application
Platform	I-Application
(	O
DJGPP	B-Application
)	O
is	O
a	O
software	O
development	O
suite	O
for	O
Intel	O
80386-level	O
and	O
above	O
,	O
IBM	O
PC	O
compatibles	O
which	O
supports	O
DOS	B-Device
operating	O
systems	O
.	O
</s>
<s>
It	O
is	O
guided	O
by	O
DJ	B-Application
Delorie	I-Application
,	O
who	O
began	O
the	O
project	O
in	O
1989	O
.	O
</s>
<s>
It	O
is	O
a	O
port	O
of	O
the	O
GNU	B-Application
Compiler	I-Application
Collection	I-Application
(	O
GCC	B-Application
)	O
,	O
and	O
mostly	O
GNU	B-Operating_System
utilities	O
such	O
as	O
Bash	B-Operating_System
,	O
find	B-Application
,	O
tar	B-Application
,	O
ls	B-Application
,	O
GAWK	O
,	O
sed	B-Application
,	O
and	O
ld	B-Device
to	O
DOS	B-Device
Protected	B-Application
Mode	I-Application
Interface	O
(	O
DPMI	O
)	O
.	O
</s>
<s>
Supported	O
languages	O
include	O
C	B-Language
,	O
C++	B-Language
,	O
Objective-C/C	O
++	O
,	O
Ada	B-Language
,	O
Fortran	B-Application
,	O
and	O
Pascal	B-Application
.	O
</s>
<s>
The	O
compiler	B-Language
generates	O
32-bit	O
code	O
,	O
which	O
runs	O
natively	O
in	O
32-bit	O
protected	B-Application
mode	I-Application
while	O
switching	O
back	O
to	O
16-bit	O
DOS	B-Device
calls	O
for	O
basic	O
OS	O
support	O
.	O
</s>
<s>
However	O
,	O
unlike	O
the	O
Open	B-Application
Watcom	I-Application
C/C	I-Application
++	I-Application
compiler	B-Language
,	O
it	O
is	O
not	O
a	O
zero-based	O
flat	O
model	O
due	O
to	O
preferring	O
NULL	O
pointer	O
protection	O
for	O
better	O
stability	O
.	O
</s>
<s>
It	O
can	O
access	O
up	O
to	O
4	O
GB	O
of	O
RAM	O
in	O
pure	O
DOS	B-Device
when	O
using	O
a	O
suitable	O
DPMI	O
host	O
(	O
e.g.	O
,	O
CWSDPMI	B-Application
r7	O
or	O
HDPMI32	O
)	O
.	O
</s>
<s>
,	O
main	O
components	O
of	O
DJGPP	B-Application
2	O
include	O
:	O
</s>
<s>
It	O
is	O
also	O
possible	O
to	O
use	O
DJGPP	B-Application
to	O
cross-compile	O
software	O
to	O
DOS	B-Device
,	O
for	O
example	O
on	O
UNIX	O
/	O
Linux	O
.	O
</s>
<s>
Both	O
the	O
DJGPP	B-Application
libraries	O
and	O
the	O
programs	O
can	O
be	O
compiled	B-Language
this	O
way	O
,	O
linked	O
and	O
then	O
deployed	O
to	O
machines	O
with	O
DOS	B-Device
or	O
DOS	B-Device
emulators	O
.	O
</s>
<s>
DJGPP	B-Application
presents	O
the	O
programmer	O
an	O
interface	O
which	O
is	O
compatible	O
with	O
the	O
ANSI	O
C	B-Language
and	O
C99	B-Language
standards	I-Language
,	O
DOS	B-Device
APIs	O
,	O
and	O
an	O
older	O
POSIX-like	O
environment	O
.	O
</s>
<s>
Compiled	B-Language
binaries	O
are	O
long	O
filename	O
(	O
LFN	O
)	O
aware	O
and	O
can	O
handle	O
such	O
names	O
under	O
most	O
32-bit	B-Application
Windows	I-Application
by	O
default	O
,	O
but	O
they	O
cannot	O
use	O
the	O
Win16	B-Library
or	O
Win32	B-Library
APIs	I-Library
that	O
graphical	O
programs	O
on	O
Windows	B-Application
need	O
.	O
</s>
<s>
terminate-and-stay-resident	O
(	O
TSR	O
)	O
programs	O
to	O
support	O
LFNs	O
under	O
plain	O
DOS	B-Device
or	O
Windows	B-Device
NT	I-Device
4	I-Device
are	O
available	O
.	O
</s>
<s>
While	O
DJGPP	B-Application
runs	O
in	O
32-bit	O
protected	B-Application
mode	I-Application
,	O
its	O
stub	O
and	O
library	O
heavily	O
rely	O
on	O
many	O
16-bit	O
DOS	B-Device
and	O
BIOS	O
calls	O
.	O
</s>
<s>
Because	O
the	O
x86-64	B-Device
versions	O
of	O
Windows	B-Application
lack	O
support	O
for	O
16-bit	O
programs	O
,	O
there	O
is	O
no	O
NTVDM	O
,	O
and	O
DJGPP	B-Application
applications	O
cannot	O
be	O
run	O
.	O
</s>
<s>
Under	O
x86-64	B-Device
systems	O
these	O
applications	O
function	O
only	O
through	O
emulation	O
(	O
e.g.	O
</s>
<s>
DOSBox	B-Application
)	O
,	O
x86	B-General_Concept
virtualization	I-General_Concept
(	O
e.g.	O
</s>
<s>
VirtualBox	B-Operating_System
)	O
,	O
or	O
similar	O
(	O
e.g.	O
</s>
<s>
Linux	O
's	O
DOSEMU	B-Application
)	O
.	O
</s>
<s>
This	O
problem	O
arises	O
because	O
in	O
long	B-Application
mode	I-Application
x86-64	B-Device
processors	O
do	O
not	O
support	O
the	O
virtual	B-Application
8086	I-Application
mode	I-Application
used	O
to	O
run	O
16-bit	O
code	O
in	O
IA-32	O
processors	O
.	O
</s>
