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SECTION
6.
9 PIN SERIAL INPUT/OUTPUT
i
I
6.1
PIN DESCRIPTION
All external dommunication peripherals connect
to the 21X through
the 9-pin serial l/O connector
(Figure
6.1-11).
Table
6.1-1 gives a brief
description of each pin's function.
srRtAt
|
/o
\_./Lt\r/\L,/t
4
3l
OCCCC
COCC
FIGURE
6.1-1. 9 Pin Connector
TABLE
6.1-1.
Pin
Description
=
Abbreviation for the
function name.
=
Pin number.
=
Signal Out
of
the 21X to
a
peripheral.
=
Signal
Into
the 21X
from a peripheral.
PIN
ABR
UO
6PEO
Description
5V:
Sources
5V DC, used
to power peripherals.
Ground:
Provides a power
return for
pin
1
(5V), and
is
used as
a reference for
voltage levels.
Ring: When
raised by a
peripheral the 21X enters
telecommunications.
Receive
Data:
Serial data
transmitted by a peripheral
are received on pin
4.
Modem
Enable:
Raised by
the
21X after the ring line has
been raised.
Description
Printer
Enable:
Raised to
enable
Storage Module or
other print device.
Ground, common
with
pin
2.
Tape
Enable:
Powers the
cassette recorder during
data
transfer to tape.
Transmit
Data:
Serial data
are
transmitted from the
21X
to peripherals on pin
9;
logic low marking (0V) logic
high
spacing (5V) standard
asynchronous
ASCll,
8
data bits, no parity,
1
start
bit,
1
stop bit,
300,
1200,
9600,
76,800 baud (user
selectable).
6
9
ABR
PIN
o
I
PIN
ABR
UO
15VO
o
RrNq
I
RXD
I
ME
TXD
O
4
6-1
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