<s>
Bravo	B-Protocol
was	O
the	O
first	O
WYSIWYG	B-Application
document	B-General_Concept
preparation	I-General_Concept
program	B-Application
.	O
</s>
<s>
It	O
provided	O
multi-font	O
capability	O
using	O
the	O
bitmap	O
displays	B-Device
on	O
the	O
Xerox	B-Device
Alto	I-Device
personal	B-Device
computer	I-Device
.	O
</s>
<s>
Bravo	B-Protocol
was	O
a	O
modal	B-General_Concept
editor	I-General_Concept
—	O
characters	O
typed	O
on	O
the	O
keyboard	O
were	O
usually	O
commands	O
to	O
Bravo	B-Protocol
,	O
except	O
when	O
in	O
"	O
insert	O
"	O
or	O
"	O
append	O
"	O
mode	O
,	O
in	O
which	O
case	O
they	O
were	O
entered	O
into	O
the	O
character	B-General_Concept
buffer	I-General_Concept
.	O
</s>
<s>
Bravo	B-Protocol
made	O
extensive	O
use	O
of	O
the	O
mouse	B-Device
for	O
marking	O
locations	O
in	O
the	O
text	O
,	O
as	O
well	O
as	O
selecting	O
areas	O
of	O
the	O
text	O
,	O
but	O
it	O
was	O
not	O
used	O
for	O
command	O
entry	O
.	O
</s>
<s>
(	O
Being	O
at	O
the	O
very	O
dawn	O
of	O
graphical	B-Application
user	I-Application
interface	I-Application
design	O
,	O
a	O
non-command	O
driven	O
interface	O
was	O
judged	O
too	O
ambitious	O
and	O
possibly	O
even	O
inefficient	O
and	O
cumbersome	O
.	O
)	O
</s>
<s>
Bravo	B-Protocol
also	O
supported	O
use	O
of	O
multiple	O
buffers	B-General_Concept
(	O
i.e.	O
</s>
<s>
Although	O
Bravo	B-Protocol
usually	O
displayed	O
the	O
text	O
with	O
formatting	O
(	O
e.g.	O
</s>
<s>
This	O
was	O
because	O
the	O
Alto	B-Device
monitor	O
provided	O
a	O
resolution	B-General_Concept
of	O
72	O
pixels	B-Algorithm
per	I-Algorithm
inch	I-Algorithm
,	O
but	O
the	O
laser	O
printers	O
used	O
at	O
PARC	O
provided	O
a	O
resolution	B-General_Concept
of	O
300	O
PPI	O
.	O
</s>
<s>
However	O
,	O
because	O
the	O
screen	O
image	O
was	O
necessarily	O
an	O
approximation	O
,	O
one	O
would	O
occasionally	O
find	O
characters	O
and	O
words	O
slightly	O
off	O
(	O
a	O
problem	O
that	O
continues	O
to	O
this	O
day	O
with	O
word	B-General_Concept
processing	I-General_Concept
systems	O
)	O
.	O
</s>
<s>
The	O
72	O
PPI	O
pixel	O
size	O
closely	O
approximated	O
the	O
72.27	O
points	O
per	O
inch	O
used	O
in	O
the	O
commercial	O
printing	O
industry	O
,	O
so	O
that	O
a	O
pixel	O
in	O
Bravo	B-Protocol
would	O
be	O
the	O
same	O
size	O
as	O
a	O
typeface	O
point	O
.	O
</s>
<s>
Bravo	B-Protocol
was	O
the	O
base	O
for	O
Gypsy	B-Protocol
,	O
a	O
later	O
document	O
system	O
on	O
the	O
Alto	B-Device
,	O
the	O
first	O
with	O
a	O
modern	O
graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
Bravo	B-Protocol
was	O
followed	O
by	O
BravoX	O
,	O
which	O
was	O
developed	O
in	O
1979	O
under	O
Simonyi	O
's	O
leadership	O
at	O
Xerox	O
's	O
Advanced	O
Systems	O
Development	O
(	O
ASD	O
)	O
group	O
.	O
</s>
<s>
BravoX	O
was	O
"	O
modeless	B-General_Concept
"	O
,	O
as	O
was	O
Gypsy	B-Protocol
.	O
</s>
<s>
While	O
Bravo	B-Protocol
(	O
and	O
BravoX	O
)	O
were	O
originally	O
implemented	O
in	O
BCPL	B-Language
for	O
the	O
Xerox	B-Device
Alto	I-Device
,	O
BravoX	O
was	O
later	O
re-implemented	O
in	O
a	O
language	O
called	O
"	O
Butte	O
"	O
(	O
"	O
a	O
Butte	O
is	O
a	O
small	O
Mesa	B-Language
"	O
,	O
as	O
Charles	O
Simonyi	O
used	O
to	O
say	O
)	O
.	O
</s>
<s>
Alto	B-Device
BCPL	B-Language
compiled	O
into	O
Data	B-Device
General	I-Device
Nova	I-Device
machine	O
instructions	O
,	O
which	O
were	O
in	O
turn	O
interpreted	O
by	O
Alto	B-Device
microcode	O
.	O
</s>
<s>
Butte	O
compiled	O
into	O
Butte-specific	O
byte	O
codes	O
,	O
which	O
were	O
interpreted	O
by	O
special	O
Alto	B-Device
microcode	O
,	O
similar	O
to	O
the	O
Mesa	B-Language
bytecode	O
interpreter	O
.	O
</s>
<s>
Early	O
versions	O
of	O
Bravo	B-Protocol
had	O
a	O
command	O
interface	O
designed	O
such	O
that	O
a	O
user	O
attempting	O
to	O
enter	O
the	O
command	O
"	O
EDIT	O
"	O
in	O
command-mode	O
would	O
instead	O
irreversibly	O
replace	O
all	O
text	O
with	O
a	O
"	O
T	O
"	O
.	O
</s>
