Theory of Operation
Serial Port 1 (COM1)
The programming architecture of both serial ports 1 and 2 is the same
as for the popular WD 8250. The baud rate generator is integral to the
serial controller, configurable for a range of baud rates up to
56 Kbaud. All of the RS-232-C signals (TXD, RXD, CTS, RTS,
DSR, and DTR) are implemented with RS-232-C drivers and
receivers and are controlled by the registers within the serial port chip.
In addition, RLSD and RI are implemented with RS-232-C receivers,
which are also controllable by registers available within the serial port
chip. This makes the serial port interface IBM-compatible.
Jumpers W23 through W28 control the orientation of this serial port
for Data Terminal Equipment (DTE) and Data Communication
Equipment (DCE). The factory ships this serial port configured as
DTE for STD DOS systems to perform COM1 operations, and as
DCE for STD ROM Development Systems to attach to an IBM PC or
compatible COM1 port. You can use optional cables ZT 90014 or
ZT 90027 to connect this serial port from the J1 frontplane connector
to another piece of RS-232-C compatible equipment.
You can use the ZT 90014 cable as a transition from J1 to a female
25-pin D-type connector, which then plugs into a male 25-pin D-type
connector such as is mounted on the IBM PC and compatibles. The
ZT 90027 cable contains a male 25-pin D-type connector, which
allows connection to a female 25-pin D-type connector on an external
device.
One difference exists between this serial port and a standard 8250
serial port: two general purpose I/O bits labeled OUT1 and OUT2
available on an 8250 are not available on the 16C452. Instead, one of
the bits in the Control register that would normally control the OUT2
signal now controls the interrupt enable for that serial port. The
OUT1 bit is a no connect. This is equivalent to the IBM PC
implementation of OUT1 and OUT2 and provides for complete IBM
PC compatibility. Refer to Chapter 8 for further details.
3-5
Содержание ZT 8809A
Страница 15: ...Tables Table B 9 J5 Pin Assignments B 17 Table B 10 J6 Pin Assignments B 18 Table B 11 J7 Pin Assignments B 19...
Страница 334: ...Jumper Configurations W49 W48 A W47 B A B W37 W66 A W50 B C J7 W67 Figure A 11 W37 W47 50 W66 W67 Jumper Blocks A 34...
Страница 346: ...Jumper Configurations W61 W60 W62 W63 W64 A B A B W65 Figure A 13 W60 W65 Jumper Block A 46...