Parallel Interface Signals - Texas Instruments 880 User Manual

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