86
IEEE 1284 Parallel Interface
Modes
The IEEE 1284 parallel
int
erface s
u
ppor
t
s
t
he follow
ing
t
wo modes.
Compatibility Mode
Compa
ti
b
i
l
it
y mode allows da
t
a
t
ra
n
sm
i
ss
i
o
n
from hos
t
t
o pr
int
er o
n
ly: Ce
nt
ro
ni
cs-compa
ti
ble.
Specification
Reverse Mode
The
t
ra
n
sfer of s
t
a
tu
s da
t
a from
t
he pr
int
er
t
o
t
he hos
t
proceeds
in
t
he
ni
bble or by
t
e mode.
Th
i
s mode allows da
t
a
t
ra
n
sfer from a
n
asy
n
chro
n
o
u
s pr
int
er
un
der
t
he co
nt
rol of
t
he hos
t
. Da
t
a
t
ra
n
sfers
in
t
he
ni
bble mode are made v
i
a
t
he ex
i
s
ting
co
nt
rol l
in
es
in
unit
s of fo
u
r b
it
s (a
ni
bble).
I
n
t
he by
t
e mode, da
t
a
t
ra
n
sfer proceeds by mak
ing
t
he 8-b
it
da
t
a l
in
es b
i
d
i
rec
ti
o
n
al. Bo
t
h modes
fa
i
l
t
o proceed co
n
c
u
rre
nt
ly
in
t
he compa
ti
b
i
l
it
y mode,
t
hereby ca
u
s
ing
half-d
u
plex
t
ra
n
sm
i
ss
i
o
n
.
Mode
Communication direction
Other information
Compatibility mode
Host
→
Printer communication
Centronics-compliant
Reverse mode
Printer
→
Host communication
Assumes a data transfer from an
asynchronous printer
Data transmission
8-bit parallel
Synchronization
Externally supplied STROBE signals
Handshaking
ACK and BUSY signals
Signal levels
TTL-compatible connector
Connector
ADS-B36BLFDR176 (HONDA) or equivalent product
Reverse communication
Nibble or byte mode
