NorthStar HORIZON Manual page 75

BAUD RATE SELECTION
Baud rates for both the standard and second serial interfaces are
specified by configuration of the Baud Rate header at location
2D. The following baud rate clocks are available on the header.
pin 16 9600
x
16
baud
pin 15
4800
x
16 baud
pin 14
2400
x
16
baud
pin 13
1200
x
16 baud
pln 12
600 x 16
baud
pln 11
300 x 16 baud
pln 10
110 x 16 baud
pin 9 150 x 16 baud or 75 X 16 baud
(selected by jumper J4 near 50)
The selected baud rate clocks should be connected to the
following serial interface clocks as required.
pln 1
pln 2
pln 3
pln 4
pin 5
pin 6
pin 7
pin 8
Special Clock connection (see schematics)
Special Clock connection
Standard Serial Interface Transmitter Clock
Standard Serial Interface Receiver Clock
Second Serial Interface Transmitter Clock
Second Serial Interface Receiver Clock
Special Clock connection
Special Clock connection
The transmit and receive clocks for a serial interface are
generally connected to the same baud rate. However, serial input
and output can be configured to occur at two different rates.
NotE' that for asynchronous communication the USARTs are generally
procrrammed to use a clock at sixteen times the desired baud rate.
Sync:hronous communication generally uses a clock the same as the
deslred baud rate.
PROC;RAMMING SERIAL I/O INTERFACES
The Dns section of the North Star System Software Manual shows
comme;1ted subroutines for the following serial I/O functions:
USAHT initialization, input one character, output one character,
and test for a break character (control-C). Note that the
inil:ialization routine initializes both the Standard and Second
Ser.al Interfaces after initializing the parity feature. The
chal:acter input and output routines are programmed for the
Standard Serial Interface.. The Second SE,rial Interface can be
simLlarly programed using I/O ports 4 and 5 instead of 2 and 3.
75 North Star HORIZON Computer