System Reference

COM-2(PC)F34

Circuitry Diagrams
TXD, RTS, DTR
RXD, CTS, DSR
SN75188
SN75189
15pF

Figure 4.1. Circuitry Diagrams

Block Diagram

The following is a block diagram of the COM-2(PC)F interface

board.

ADDRESS
DECODER
DATA
BUFFER
Data Bus
(D7~D0)
IBM-PC/AT BUS
CNTROL
BUFFER
Addr. Bus
(A9~A3)
AEN
Addr. Bus
(A2~A0)
IOR
IOW
RESET
NS16550
CLOCK
COM-2(PC)F
CN1
Serial Port
CN2
Serial Port
NS16550
RS-232C
DRIVER &
RECEIVER
RS-232C
DRIVER &
RECEIVER
INTERRUPT
JUMPER
INTERRUPT
VECTOR
REGISTER
IRQ3~7,
IRQ9~12,
IRQ14, 15

Figure 4.2. COM-2(PC)F Block Diagram