TRS-80 MODEL III
RS-232-C Pin Location
Looking from the outside at the RS-232-C
jack
on the Model III Computer:
Parallel
Printer
Interface
Signal
Function
Pin#
STROBE*
1.5
IJ-S
pulse
to
clock
the
data
from
1
processorto printer
DATA
0 Bit 0
(Isb)
of
output data
byte
3
DATA 1
Bit 1of output data byte 5
DATA 2
Bit 2 of output data byte
7
DATA 3
Bit 3 of output data byte 9
DATA 4
Bit4 of output data byte
11
DATA 5
Bit 5 of output data byte 13
DATA 6
Bit 6of output data byte
15
DATA 7
Bit 7 (msb) of output data byte 17
BUSY
Inputto Computer
from
Printer,
high
21
indicates busy
PAPER
Inputto Computer
from
Printer,
high
23
EMPTY
1ndicates
no
paper- if Printer doesn't
provide this, signal
is
forced
low
SELECT
Input
to
Computer
from
Printer,
high
25
indicates device selected
FAULT*
Inputto Computer
from
Printer, low 28
indicates fault (paper empty, light
detect, deselect, etc.)
GROUND
Common signal ground
2,4,6,8,10
12,14,16,18,
20,22,24,27,
31,33,34
NC
Not connected or not
used
26,29,30,32
*These signals are active-low.
14/2
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