Operator`s manual

6-1
SECTION 6. 9 PIN SERIAL INPUT/OUTPUT
6.1 PIN DESCRIPTION
All external communication peripherals connect
to the 21X through the 9-pin serial I/O connector
(Figure 6.1-1). Table 6.1-1 gives a brief
description of each pin's function.
FIGURE 6.1-1. 9 Pin Connector
TABLE 6.1-1. Pin Description
ABR = Abbreviation for the function name.
PIN = Pin number.
O = Signal Out of the 21X to a peripheral.
I = Signal Into the 21X from a peripheral.
PIN ABR I/O Description
1 5V O 5V: Sources 5V DC, used
to power peripherals.
2 G Ground: Provides a power
return for pin 1 (5V), and is
used as a reference for
voltage levels.
3 RING I Ring: When raised by a
peripheral the 21X enters
telecommunications.
4 RXD I Receive Data: Serial data
transmitted by a peripheral
are received on pin 4.
5 ME O Modem Enable: Raised by
the 21X after the ring line has
been raised.
PIN ABR I/O Description
6 PE O Printer Enable: Raised to
enable Storage Module or
other print device.
7 G I/O Ground, common with pin
2.
8 TE O Tape Enable: Powers the
cassette recorder during
data transfer to tape.
9 TXD O Transmit Data: Serial data
are transmitted from the
21X to peripherals on pin 9;
logic low marking (0V) logic
high spacing (5V) standard
asynchronous ASCII, 8
data bits, no parity, 1 start
bit, 1 stop bit, 300, 1200,
9600, 76,800 baud (user
selectable).