<s>
C-Modem	B-Protocol
is	O
a	O
protocol	O
driver	O
developed	O
by	O
Lavio	O
Pareschi	O
(	O
Rio	O
de	O
Janeiro	O
)	O
in	O
1989	O
,	O
that	O
works	O
similarly	O
and	O
better	O
than	O
ZMODEM	B-Device
.	O
</s>
<s>
It	O
includes	O
a	O
whole	O
new	O
file	B-Protocol
transfer	I-Protocol
protocol	I-Protocol
,	O
built	O
around	O
the	O
idea	O
of	O
crash	O
recovery	O
,	O
easy	O
of	O
use	O
and	O
great	O
performance	O
.	O
</s>
<s>
C-Modem	B-Protocol
provides	O
reliable	O
file	O
transmission	O
even	O
in	O
the	O
worst	O
conditions	O
,	O
as	O
it	O
adapts	O
itself	O
immediately	O
to	O
any	O
errors	O
that	O
may	O
occur	O
(	O
even	O
in	O
the	O
so-called	O
'	O
error	O
free	O
 '	O
modems	O
)	O
.	O
</s>
<s>
Major	O
features	O
of	O
the	O
C-Modem	B-Protocol
communications	O
protocol	O
include	O
:	O
</s>
<s>
Being	O
interrupted	O
by	O
any	O
condition	O
,	O
the	O
file	O
transmitted	O
is	O
saved	O
with	O
the	O
extension	O
file	O
.BAD	O
until	O
the	O
last	O
byte	B-Application
is	O
received	O
correctly	O
.	O
</s>
<s>
Depending	O
on	O
velocity	O
and	O
errors	O
during	O
transmission	O
,	O
as	O
well	O
as	O
line	O
conditions	O
,	O
the	O
size	O
of	O
data-blocks	O
between	O
crc-blocks	O
will	O
freely	O
vary	O
from	O
32	O
to	O
4096	O
bytes	B-Application
.	O
</s>
<s>
This	O
reduces	O
the	O
amount	O
of	O
control	O
bytes	B-Application
added	O
to	O
the	O
transmission	O
and	O
minimizes	O
data	O
repetition	O
.	O
</s>
<s>
While	O
not	O
accurate	O
in	O
terms	O
of	O
bits	O
(	O
it	O
rounded	O
up	O
)	O
,	O
the	O
file	O
was	O
accurate	O
in	O
terms	O
of	O
bytes	B-Application
,	O
and	O
would	O
have	O
exactly	O
the	O
same	O
size	O
as	O
the	O
original	O
one	O
as	O
it	O
up/downloaded	O
.	O
</s>
<s>
To	O
its	O
credit	O
,	O
it	O
did	O
not	O
add	O
bytes	B-Application
to	O
complete	O
blocks	O
of	O
fixed	O
size	O
.	O
</s>
