<s>
CodeView	B-Application
is	O
a	O
standalone	O
debugger	B-Application
created	O
by	O
David	O
Norris	O
at	O
Microsoft	O
in	O
1985	O
as	O
part	O
of	O
its	O
development	O
toolset	O
.	O
</s>
<s>
It	O
also	O
shipped	O
with	O
Visual	B-Language
Basic	I-Language
for	O
MS-DOS	B-Application
,	O
Microsoft	B-Language
BASIC	I-Language
PDS	I-Language
,	O
and	O
a	O
number	O
of	O
other	O
Microsoft	O
language	O
products	O
.	O
</s>
<s>
It	O
was	O
one	O
of	O
the	O
first	O
debuggers	B-Application
for	O
MS-DOS	B-Application
to	O
be	O
full-screen	O
oriented	O
,	O
rather	O
than	O
line-oriented	O
(	O
as	O
Microsoft	O
's	O
predecessors	O
DEBUG	B-Device
and	O
SYMDEB	O
or	O
Digital	O
Research	O
's	O
SID	O
)	O
.	O
</s>
<s>
When	O
running	O
,	O
CodeView	B-Application
presents	O
the	O
user	O
with	O
several	O
windows	O
that	O
can	O
be	O
tiled	O
,	O
moved	O
,	O
sized	O
and	O
otherwise	O
manipulated	O
via	O
the	O
keyboard	O
or	O
mouse	O
,	O
with	O
CodeView	B-Application
4.x	O
providing	O
a	O
richer	O
interface	O
.	O
</s>
<s>
Command	O
window	O
–	O
user	O
commands	O
(	O
using	O
the	O
same	O
or	O
similar	O
syntax	O
as	O
DEBUG	B-Device
and	O
SYMDEB	O
)	O
could	O
be	O
entered	O
here	O
.	O
</s>
<s>
Register	O
window	O
–	O
to	O
visualize	O
the	O
80x86	B-Operating_System
register	O
contents	O
,	O
including	O
segments	O
,	O
flags	O
and	O
the	O
FPU	B-General_Concept
(	O
CodeView	B-Application
existed	O
before	O
MMX	B-Architecture
and	O
other	O
SIMD	B-Device
extensions	O
)	O
.	O
</s>
<s>
Monochrome	O
monitor	O
support	O
–	O
allows	O
debugging	O
on	O
either	O
a	O
single	O
color	O
(	O
CGA	O
,	O
EGA	O
or	O
VGA	O
)	O
monitor	O
with	O
page/memory	O
swapping	O
between	O
the	O
user	O
application	O
and	O
the	O
CodeView	B-Application
screen	O
,	O
or	O
using	O
a	O
separate	O
monochrome	O
monitor	O
.	O
</s>
<s>
CodeView	B-Application
handles	O
all	O
program	O
models	O
,	O
including	O
TINY	O
,	O
SMALL	O
,	O
COMPACT	O
,	O
MEDIUM	O
,	O
LARGE	O
and	O
HUGE	O
,	O
with	O
TINY	O
(	O
DOS-based	O
.COM	O
files	O
)	O
having	O
their	O
symbolic	B-Application
debugger	I-Application
information	O
stored	O
in	O
a	O
separate	O
file	O
,	O
with	O
all	O
of	O
the	O
other	O
.EXE	O
formats	O
containing	O
the	O
symbolic	O
information	O
directly	O
inside	O
the	O
executable	O
.	O
</s>
<s>
CodeView	B-Application
version	O
3.x	O
and	O
4.x	O
introduced	O
various	O
transport	O
layers	O
,	O
which	O
removed	O
some	O
of	O
the	O
memory	O
space	O
limitations	O
to	O
this	O
form	O
of	O
symbolic	O
debugging	O
.	O
</s>
<s>
Typically	O
the	O
debugger	B-Application
runs	O
in	O
the	O
lower	O
640KB	O
memory	O
space	O
alongside	O
the	O
application	O
being	O
debugged	O
,	O
which	O
greatly	O
decreases	O
the	O
amount	O
of	O
memory	O
available	O
to	O
the	O
application	O
being	O
debugged	O
.	O
</s>
<s>
The	O
transport	O
layer	O
allows	O
only	O
a	O
stub	O
to	O
exist	O
in	O
main	O
memory	O
,	O
while	O
the	O
bulk	O
of	O
the	O
debugger	B-Application
code	O
resides	O
in	O
EMS	O
or	O
XMS	O
(	O
memory	O
above	O
the	O
1MB	O
barrier	O
,	O
or	O
outside	O
of	O
the	O
normal	O
0KB	O
-	O
640KB	O
address	O
space	O
typically	O
used	O
by	O
DOS	O
programs	O
)	O
.	O
</s>
<s>
CodeView	B-Application
also	O
came	O
with	O
a	O
CVPACK	O
command-line	O
utility	O
,	O
which	O
can	O
reduce	O
the	O
size	O
of	O
the	O
CodeView-generated	O
information	O
internally	O
,	O
while	O
still	O
retaining	O
full	O
symbolic	O
access	O
to	O
data	O
.	O
</s>
<s>
Microsoft	O
released	O
Visual	B-Application
C++	I-Application
1.0	O
with	O
CodeView	B-Application
functionality	O
integrated	O
directly	O
into	O
a	O
single	O
programming	B-Application
environment	I-Application
,	O
known	O
as	O
the	O
Integrated	B-Application
Development	I-Application
Environment	I-Application
(	O
IDE	O
)	O
--	O
though	O
CodeView	B-Application
was	O
still	O
available	O
in	O
the	O
16-bit	O
versions	O
of	O
Visual	B-Application
C++	I-Application
.	O
</s>
<s>
QuickC	B-Application
and	O
a	O
number	O
of	O
other	O
development	O
tools	O
in	O
the	O
'	O
Quick	O
 '	O
series	O
also	O
supported	O
this	O
move	O
to	O
a	O
single-source	O
IDE	O
,	O
what	O
became	O
the	O
precursor	O
to	O
the	O
modern	O
Visual	B-Application
Studio	I-Application
developer	O
environment	O
,	O
as	O
well	O
as	O
the	O
model	O
for	O
countless	O
other	O
developer	O
toolsets	O
.	O
</s>
<s>
Today	O
,	O
the	O
debugger	B-Application
is	O
considered	O
an	O
integrated	O
and	O
essential	O
part	O
of	O
the	O
Microsoft	B-Application
Visual	I-Application
Studio	I-Application
family	O
of	O
products	O
,	O
and	O
owes	O
its	O
true	O
roots	O
to	O
CodeView	B-Application
,	O
and	O
the	O
enhancements	O
seen	O
in	O
version	O
4.x	O
specifically	O
.	O
</s>
<s>
It	O
had	O
over	O
30	O
commands	O
,	O
and	O
was	O
described	O
by	O
PC	O
Magazine	O
as	O
a	O
step	O
up	O
from	O
DEBUG	B-Device
.	O
</s>
<s>
Codeview	B-Application
in	O
turn	O
was	O
described	O
as	O
"	O
a	O
fullscreen	O
SYMDEB	O
"	O
.	O
</s>
