Serial Port; Serial Port Components - Sun Microsystems Sun Blade 1000 Service Manual

C.1.13

Serial Port

The workstation incorporates two serial ports. Each serial port is synchronous and
asynchronous with full modem controls. All serial port functions are controlled by a
serial port controller that is electrically connected to the system through the EBus.
Line drivers and line receivers control the serial port signal levels and provide RS-
232 and RS-423 compatibility. Each serial port interfaces through its own DB-25
connector.
The major features of each serial port include:
Two fully functional synchronous and asynchronous serial ports
DB-25 connectors
Increased baud rate (to 384 Kbaud synchronous, 460.8 Kbaud asynchronous)
Variable edge rate for greater performance
EBus interface
The following figure shows a functional block diagram of the serial port:
FIGURE C-11
C.1.13.1

Serial Port Components

Serial port components include a serial port controller, line drivers, and receivers.
The serial port controller contains 64-byte input and output buffers that reduce the
CPU bandwidth requirements of the serial port controller.
C-34 Sun Blade 1000 and Sun Blade 2000 Service Manual • January 2002
Port A
EBus
Serial port
controller
Port B
Serial Port Functional Block Diagram
Line
receiver
RS-232/423 select
Line
driver
Slew rate select
Line
receiver
Serial port A
DB-25
EMI
filter
Serial port B
DB-25
EMI
filter