Tandy 1400LT - RS232 C Interface Circuit; Internal Modem Connector and Peripheral Circuitry

RS232C Interface Circuit
The TANDY 1400LT use DS 14C88/DS14C89AN for Line Driver/Receiver.
The DS14C88/DS 14C89AN translates standard TTL or CMOS logic levels to/from levels conforming to RS232C.
Figure 4-41 shows RS232C interface circuit.
RTS “A
TW *ZA
DTR *PA
-12v
IC47
Figure 4-41. RS232C Interface Circuit
Figure 4-42 shows internal modem connector and peripheral circuitry.
‘F15R
m
RXDR
RXDM
ISSAR
IlsRR
m
m
MODm
RA12
+5v
m
RXD
m
m
CN15
TXDM
RXDM
m
m
m
m
MODEM
N.C
AUDIO
DIREC
GND
+5v
GND
+5v
GND
+ 12v
GND
-12v
N.C
N.C
Figure 4-42. Internal MODEM Connector and Peripheral Circuitry
4-52