Radio Shack TRS-80 Model II Reference Manual page 247

Technical Information
Model II/Model II Communications
For hard-wiring between two Model II's without a modem, use the wiring
arrangement described below (Model II to Model II only)
DB-25 MALE CONNECTOR
CONNECT TO RS-232 MODEL II
13
25
•••••••••••
••••••••••
DB-25 CONNECTOR
14
I
~
....
'"
<Xl
~
'" '"
w
~
I
0
I
I
I
~
....
<Xl
'" '"
~
w
'"
~ I
0
DB-25 MALE CONNECTOR
CONNECT TO CHANNEL A
MODEL II
Connection Diagram, Modell! (Channel A or B) to Modell!
(Channel A or B). Use stranded wire, 24-gauge, to connect
two DB-25 connectors as illustrated_ If wire length exceeds 50
feet, twist lines 7
(GND),
2 (TO) and 3
(AD).
Refer to the Modell!
Operation Manual for a description of signals available.
In addition, if you are only going to use one of the serial channels, pins 3,5,6,
7, and 8 on the other channel must be tied together before you initialize the
channels with
SETCOM
or
RS232C.
Prepare a DB-25 male terminator plug for
the unused channel:
8 7 6 5 3
urn
13
25
•••••••••••
•••••••••••
DB-25 CONNECTOR
CONNECTTOCHANNELB
14
MODEL II
JUMPER DIAGRAM
DUMMY TERMINATOR FOR MODEL II
(SERIAL TERMINATOR PLUG)
283