Table 7-4. Parallel
Interface
Signals
Signal
Return
Pin
Pin
Source
Signal
Description
19
H
STROBE-
Positive-going edge latches the 8 data
bits and turns
BUSY on (DEMAND off).
2
20 H DATA1
Eight high-active
3
21
H
DATA2
parallel inputs.
DATA
1
4
22
H
DATA3
is
the
least significant
5 23 H
DATA4
bit.
DATA8
is the most
6
24
H
DATA5
significant bit.
DAT
A8
7 25 H
DATA6
is used only when
8 26 H
DATA7
configuration code 39,
9
27 H
DATA8
3B, or
3A
is enabled.
10
28 P
ACK-
Normally high. Pulsed
low
when:
1. Printer
is
ready
to
receive data.
2.
Printer
is
placed on line.
11
29 P BUSY When printer cannot receive data,
it
signals BUSY. Possible reasons:
1. Printer is
off
line.
2. Data
not
yet
acknowledged.
3. Data buffer
at
BUSY limit.
4. Printer in Command mode.
5.
Printer
out
of
paper.
6.
Mechanical fault.
12
P
PE
(Paper Empty)
High when paper-out switch is acti-
vated.
13 P
SLCT
High when printer is
on
line.
16 SIGNAL GROUND Tied
to
dc
power supply ground. Refer-
ence ground
for
all interface signals.
17
CHASSIS GROUND
Tied
to
earth ground.
18
+5Vdc
For
interfa~e
circuits. Should be limited
to
100mA.
31
30 H
INIT-
Normally high.
When
pulsed low,
printer resets and does power-up diag-
nostics and goes on
line
if
configuration
code 9B is
ON.
P = Printer
.
H = Host
7-5
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