Sun Microsystems Sun Workstation 100U System Manager's Manual page 133

Sun 100/150 Installation Manual Hardware Configuration and Expansion
Note that older workstations (pre-1.0 Release) have only two serial ports - serial port A is
configured as a DOE (Data Oomm unications Equipment) and serial port B is configured as a
DTE. In addition, only serial port A on the older workstations has rull modem control. This
means that external cables built ror the Sun-lor Sun-1.5 CPU either may have to
be
modified
to work correctly with the Sun-2 CPU, or a null modem cable may be required.
The serial ports on the Sun Workstation were designed primarily ror connecting output peri-
pherals - such as terminals, modems, printers, and plotters - and can drive these output lines
at speeds up to 19.2 Kbaud. All ports provide the CTS, RTS, DTR, DSR, and DCD control
lines required by some devices (such as modems) in addition to the transmit and receive lines;
the ports generate DTR and RTS, and pay attention to DSR, CTS, and DCD. All ports are
wired
a5
DTE (data terminal equipment) ports, and thus permit direct connection or modems
and the like (25 pins straight through). Computers and other DTE devices can be connected by
using the null modem cable supplied with your Sun system, or any similar null modem cable.
The null modem cable provided by Sun has pins 2 and 3 crossed, 4 and 5 crossed, and 6 and 20
crossed; pins 1 (Frame Ground) and 7 (Signal Ground) are carried through.
On the CPU Board, I/O channels A and B appear on 50-pin connector Jl. The pin assignments
ror Jl are:
Table 8-1: Pin Assignments ror Jl on the CPU Board
Jl
Pin
Signal
Pin Signal
3 TxDA
28
TxDB
4 DBA 29 DBB
5 RxDA 30 RxD B
7 RTSA 32 RTS B
8 DDA 33 DD B
9 CTS A 34 CTS B
11 DSR A
36
DSR B
13 GNDA 38 GNDB
14 DTR A 39 DTRB
15
DCDA
40
DCDB
22 DAA 47 DAB
24 BSY A 49 BSYB
Connector pins not mentioned are not connected tp anything.
The flat cables that connec.t to Jl on your CPU board convert this pinout to standard RS-232
pin assignments. The channels are implemented with three Zilog Z8530 dual UART chips. See
the Zilog Serial Communications Controller Technical Manual (available rrom Sun Microsys-
tems, Part Number: 800-1052-01) for programming information.
Getting tt." cabling right is a. problem that should be familiar to anyone who has had to connect
RS-232 equipment; sometimes it is most easily solved by experimenting. A piece or equipment
known as an EIA Interrace Adapter and Monitor - or, colloquially, a 'breakout box' - is
invaluable in these exercises. Consult a hardware technician or Sun Microsystems ir you need
Revision H or 12 March 1984
8-9